Thanks for reading!

This is a good question, and I have a super long answer that's been in my head for like 8 years about how to influence your teammates to adopt good engineering practices.

The short answer is that most useful software engineering practices are a risk to the first person on the team to adopt them. For example, if everyone on your team thinks automated testing is stupid and you adopt automated testing, it will look like your work is worse because you're slower in the short-term, and maybe you have to do even more work when teammates break your tests.

It comes down to accruing social currency with your team. Your teammates don't want to take a risk for you if you have a history of bad ideas that wasted everyone's time. But if, for example, you implemented automated deploys to replace a tedious workflow developers had to do manually, people would see how your ideas have payoff, and they're more willing to invest a little bit if they expect ROI long-term.

When I've convinced my teammates to invest in design docs, I made sure I had some wins under my belt before I started pushing for everyone to write design docs. I invested a lot in docs myself so my teammates could see the value before I asked them to start writing.

This is also a place where you have to think about politics a bit. Documentation has a much better shot if it has support from the top, so think about the pitch to your manager or dev lead about how design docs make their jobs easier.