I wrote a blog post about this forever ago[0] summarizing what I've seen work.
The most important thing to realize is how success will be measured. It will no longer be your individual contributions. Instead, you will be measured by how successful your team is. So you need to use your time to make your team more effective.
So the most important thing you can do is prevent anyone from becoming blocked. The next-most important thing is unblocking people when they become blocked.
How do you prevent people from becoming blocked? Make sure that everyone knows where they are going, and they know what to do when they get there. Make sure everyone knows what they are working on, and what they will be working on next. Promote good practices, and ensure that processes have consistent documentation.
How do you unblock people? Review their code quickly. Learn to differentiate "I don't want you to submit this because I don't prefer this" (bad attitude) from "I don't want you to submit this because it's going to have a negative consequence"). Learn how to phrase that second sentence in a way that doesn't make your coworkers dread getting reviews from you. Spend your time fixing tech debt that's adding drag to the team.
As you do this more, you should also make sure that people on your team are growing. Give them harder tasks than they had before. Ensure that junior engineers are getting mentored. Correct imbalances: if a specific engineer is always taking notes in meetings, create a notes rotation so that everyone has to do it.
[0] https://www.bitlog.com/2017/10/12/what-does-a-tech-lead-do/