Sync web app with mobile app?

Question

Android

Hello everyone. I would like to know the approaches when there is a web app and the user works under his account, adds some data, updates, deletes, etc. After that, he can work in the Mobile app under his account. The question is how data synchronization is usually done? if the mobile app can be offline and then the Internet appears and synchronization should occur. I would like to hear examples or solutions approaches. Thanks to everyone who will help figure it out.