정답은 app/_layout.tsx 라고 합니다.
공식 문서에서도 그렇게 설명하고있네요. 참고하시길 바랍니다.
From the reactnative community on Reddit
Explore this post and more from the reactnative community
www.reddit.com
File-based routing
Learn about Expo Router which is a file-based routing system and how to use it in your project.
docs.expo.dev