How can I get better on the direction axis to get to staff engineer?

Two broad approaches here:

1. Create/invent a new project where you will inherently determine the direction, since you have the most context.
2. Shape the (engineering) direction on an existing project. This requires taking the time to build relationships, deliver high quality work, and use the resulting trust to shape the engineering.

By definition, direction requires that people understand and agree with your approach. That means you need to talk to people. Writing emails and writing code is not enough.

Funnily enough, I actually think how the question is framed shows a bit of the gap between L5 and L6. When you're a true staff engineer, you need to care about the entire team's charter, not just individual projects. When an L6 suffers, the entire team suffers. This means that you have to care about a collection of projects (often by working through L5s), not just one.

To make things clearer, I'll dive a little into my experience working on Instagram Ads. Different teams (M1 scope with an L6 engineer) would own different parts of the ad (Oversimplification: 1 team owned the media, 1 team owned the CTA button, etc), and each team had core metrics to increase the effectiveness of their portion by X% leading to Y% more revenue.

There's often times no single project that will single-handedly get a team to its half-long or year-long goal, especially at a bigger company like Pinterest and definitely not in a mature org like Instagram Ads. The L6 engineers in this org would figure out the collection of projects the team should work on to try and hit that core goal, often times with a common theme behind them (i.e. "Why are we taking these 5 bets instead of these other 5 bets?"). They would oversee the execution of all the projects at a high-level and maybe get into the weeds and be the core POC on the biggest one.

This more holistic thinking at the team scale vs. the individual project scale is key to becoming a staff engineer. In terms of how to unlock this vision, I recommend working backwards from the team's OKRs/KPIs and building a deep understanding of your team's product space by talking with your PM/designer. Another thing to do is to figure out how you can influence other L5s and lead them.