There is no complete solution, you can check my ramblings here and probably on many other places.

You start by enabling any kind of backups you can have, to Google, to Samsung, (or even do the transfers directly in the happy case when you have the old phone with all the data and want just to transfer to new phone). You grab everything you can from the shared storage (or any storage you can grab data from), starting with direct transfer, then syncthing, adb, whatever.

You follow countless manual backup/recovery processes, each different, for everything from big apps like Whatsapp to a fancy digital clock or your basic launcher (note: it’s got to be something like Nova or some other third party launcher, because if you’re using for example Google’s launcher and anything but the latest Android 14 you can’t access in any way the data from your launcher, your “desktop”, for your security, you have to re-do your screens!).

And then, after you use all the available tools for backup, both for “all” phone (which is very far from all), for the shared data, and many, many backup/restore processes for individual apps, after you log yourself in (painfully sometimes) in many, many apps - you STILL find weeks after your put successfully everything back a lot of stuff that’s missing (sometimes at the worst times when you can’t even fix the issues, like all the offline maps in Google Maps gone, even if you are back signed in and everything with the same account, and now you don’t have good internet to even download them)!

I use Free File Sync to backup my phone. You could tell it to copy absolutely everything if you don’t know what is important and what isn’t.

Probably an adb backup with app data.

Most apps will have an account and sync system built in, Firefox for example has one, Google Keep, etc…