How can I find / transfer a single app's data files to a new phone? (unrooted)

I just got a new phone and I was able to have almost all my apps and data transfer over without an issue. Neither phone has root access.

But a couple apps (a game, a cocktail app) didn’t transfer their data and don’t have sync options.

I’ve looked through File Explorer but I can’t seem to find an obvious folder for app data. I swear this used to be accessible but I assume it got changed around at some point.

I have dev knowledge so if I need to use adb or something I can. That said, ideally I can do this wirelessly because the old phone can’t seem to be found by my computers.

1. How do I find the data files for an app?
2. Once I have the files, are there any extra steps beyond copy/paste like permissions or using adb?