Flutter and React Native both let a team share most of an app across iOS and Android. Flutter is a strong fit when the interface should be consistent and the team is ready to work in that toolkit. React Native is a strong fit when the team already lives in JavaScript and the product can use that.
The framework does not decide the product. Accounts, offline behaviour, and store release are the same problem in both. Pick the one the people who will maintain the app can actually change six months later.
If nobody on the team will keep the app, the choice should include who that person will be.