How to answer behavioral questions on situations you have never faced?

Ryan's answer is great - understanding what the question is trying to get at, highlighting them in your response, and connecting them with real experiences will go a long way.

I want to provide a couple examples of good answers given a situation like yours. To set the context, here's a little more about what "Tell me about a time you built a cross-functional feature that influenced other teams" might be trying to get at if I were asking this as a hiring manager:

• Does the candidate have an understanding of their relationship as a SWE with surrounding roles (can include Product Management, UX, QA, Marketing, Customer Support, Design) and how communication plays an important role?
• How much of the software lifecycle does the candidate have a grasp on?
• How much of the technical details were they involved in and are they able to communicate them well?
• Do they understand their feature and the impact it had on other teams?

Here are two examples of quality responses from a new grad hire that I think highlights their potential for a cross-functional opportunity even though they themselves might not have had the experience:

• "I haven't yet had the opportunity to work fully cross-functionally myself, but I did write a major part of a feature my manager owned that did. I joined the project when it was in the implementation phase, and I had to ramp up quickly to understand the design, the user requirements, and the technical stack in order to help with the effort. I attended weekly cross-functional meetings where I shared status updates and resolved issues about the design that I identified while working on the feature. I also had to create a test plan for my portion of the feature for the QA team that they were able to successfully execute tests with. This work didn't impact another team directly, but it did result in 100 users using the new feature."
• "My internship experiences so far haven't required cross-functional collaboration because my projects were experimental engineering features. However, if I were to work with a cross-functional team, I would make an active effort to make sure that the technical aspects of the feature we were building were able to support the product and design goals, and if not, I would reach out to communicate my concerns and provide possible alternatives. Though my manager was not technically a cross-functional partner, the experimental engineering feature I worked on required me to work with them to figure out how our technical stack could support the user requirements that they gave me. The experiment ended up not being worthwhile to be released by my team, but if it was a worthwhile investment because if it did succeed, it would've impacted my team in X way."

Both of these answers demonstrate communicative initiative, an understanding of the software development lifecycle, and a contextual understanding of who the stakeholders for their work are.

What about for each type of question you’re worried about assessing what the fundamental skills are and repeating them back to the interviewer, honestly acknowledging if you haven’t faced that exact scenario, but then saying here is xyz I’ve done that demonstrated those skills and that had abc great results.

For example, “the important thing to build a cross functional feature is great planning, communication, and empathy - and while it wasn’t cross functional I’ve built those skills on a project with one other coworker or student or professor by <fill in here with real example you are proud of>.

Trying to speak about something as if you did it without really having done it would likely lead to follow up questions that would go down hill.

Last thought: admitting honestly when you don’t know something or haven’t done something could even be a positive signal. It’s good if someone knows what they don’t know, it’s good if someone is honest, has courage to admit they are wrong or don’t know or need help. Interviewing for my Junior year internship at Zillow there was a follow up question on C++ vs Java and I said “I don’t know”. And they paused and wrote that down and then just asked a different question. I thought I failed because of that (and wasn’t perfect overall) but got the offer and lesson learned it’s ok to not know something.

Bonus last thought: our CTO at Mistplay was head of engineering at Airbnb in 2019-2021 and before that lead the team at Match through acquiring Tinder and a full rewrite of it. One thing he emphasized for us in his first months is he doesn’t know everything and readily admits when he needs help from the team where they know more. Obviously we need to give good answers to most interview questions, but this is a helpful mindset once on the job.

You don't need to invent a story. In fact, I'd advise against that for the exact reason you mentioned -- you don't want to trigger suspicion that you're dishonest.

I'd be upfront that you haven't faced that exact situation, but then talk about how you would solve it.

I haven't been in that exact situation, but I can share a related story that would help me navigate this.

Since you're an intern (or looking for a new grad role), this is a totally fine answer! I wouldn't expect you to have encountered every situation if you're so early in your career.

As a side note, I recommend writing down 3-4 stories before any kind of behavioral interview. These stories showcase various situations you've been in and some positive qualities you exhibited. Make sure you can talk about these stories eloquently, and then bring these up liberally in conversation.

As others have mentioned, honesty is the best policy, especially with good interviewers (which top tech companies will have) who are great at reading people and identifying when they're lying. Back when I was an interviewer, I would automatically reject people who I was >50% sure wasn't telling the truth or was cheating. Letting in that kind of candidate is immensely damaging to the company, so why take the risk?

Anyways, here are 2 angles you can approach this situation with:

1. Describe how you would react to that situation if it were to hypothetically come up
2. Bring up a story that's somewhat similar to it

Tactically, you might want to ask for permission before diving into those though (the interviewer might just want to ask you another question instead). So you can say something like "I haven't encountered that situation before, but I have gone through something somewhat similar and can use my experience there to describe what I would do in your situation. Is it okay if I jump into that?".

Here's more resources on behavioral questions: [Taro Top 10] Behavioral Interviews