Ask HN: I'm changing my job after a 15-year tenure. How should I proceed?

Hello HN, I've been at my current company for the past 15 years. I've taken on different roles where I started as a software engineer, before being promoted to lead, and then to staff engineer. I know my current company by heart. I know how to get things done. I know who to talk to and how to talk to the right people. I know the processes of my company in and out.

I decided to get out of my comfort zone. Try something new, I told myself on and on for the past 3 years. And I finally did it. I'm changing jobs.

I'm going to a new company, where I'll be doing something slightly similar to my previous role, but in a totally new field. I don't know anyone there. The people seem extremely friendly and fun to work with. This is what I felt in the hiring process.

It feels like I forgot how I got good at this. Technically, I have no doubts to get things done. However, on the people level, I have no clue how to get started. How do I make "new friends" at work?

What do you usually do when you switch to a new company? How do you go from the "new clueless person at work" to "oh hey Mike, I'll need your help this afternoon"?