What's the guaranteed way to get referrals through cold reach outs on LinkedIn?

There is so much value you could offer!

• Ask about their life, or about a specific project they worked on. People like to talk about themselves
• Ask for feedback on a project or idea that they are specifically equipped to answer
• Offer your expertise on a topic, e.g. if you have published a bunch of Android apps or you're very good with SEO, offer to share your knowledge with them
• Just compliment them for something they wrote or built.

Some great answers here: How to get referrals?

BTW, at some point in the next few months, I want to make a course on LinkedIn. As someone who uses LinkedIn 10 times a day for years now, I have lots of thoughts on how to use the platform for maximum benefit.

It's impossible to make it guaranteed, but the most powerful way to boost your chances is to provide value in return as you mentioned in your post. For inspiration and tips on how to frame the message, I highly recommend the "Favors" section of my question asking course which starts with this lesson: https://www.jointaro.com/course/ask-great-questions-that-get-great-answers-quickly/put-them-on-a-pedestal/

Zooming out, I recommend not over-indexing on referrals as cold referrals aren't that effective in this economy. I think it's higher ROI to just apply to a job ASAP when they're fresh as many recruiters will just stop taking resumes after 250 to 500 (but they'll leave the job open just in case). Check out this lesson from the job searching course: https://www.jointaro.com/course/ace-your-tech-interview-and-get-a-job-as-a-software-engineer/referrals/

I recommend the lesson about cold messaging as well: https://www.jointaro.com/course/ace-your-tech-interview-and-get-a-job-as-a-software-engineer/cold-messages/