How to remove an app and keep its data on Poco F1 with Android 11 ?

Use an application like package manager to see the package name of your desired application, memorize it, use a file manager and go to Android/data/AndLookForThePackageName, change just one letter of the package name (example: if the package name is `com.whatsapp` rename it to `com.whatsapp1`)
Delete the remove the application safely, then you can rename the folder as it was before adding the 1

Mod Edit:
It's hard nowadays to access the /data & /obb and this method can keep some data of perhaps a few social media & chat apps, but not settings/preferences, most apps nowadays barely save anything useful there, so this is not exactly a solution, backing up the data with dedicated apps sometimes work, as long as the app/game allows it, otherwise > Root (the actual data is located in /data/user/0/PackageNameOfTheApp - reachable only with root access).