What is the most efficient way to create Mobile and Web app in Flutter with the same codebase?

Suppose I am building a social media app that has different UI/UX for Web and Mobile but on small scale components is the same like posts for example, what is the best way to build the web and mobile app with the same codebase but with taking into consideration the fact that UI/UX for Web is different and Many Settings are different like push notifications, shared preferences and many more.

Is it even possible to have it in the same codebase?