There’s really nothing post-install you have to do. It’s all going to depend on what you want to do or accomplish. As an example, installing Nvidia drivers if you’re not a gamer, or need the compute functions, nouveau drivers work just fine. But, also, if you installed from the live iso with nvidia proprietary already loaded/installed that might not be necessary.
If you installed with btrfs it’s fine and btrfs snapshots can be useful. There are plenty of articles explaining pros and cons so I won’t get into that. Personally I opted for ext4, I didn’t need anything btrfs offered shrug
Finally there are a lot of “tips and tricks” out there and as far as that goes I’d just say before you go just installing a bunch of software and making a bunch of config changes make sure you read up on what it is they are telling you to do and decide if it makes sense for you to do it. Maybe it’s telling you to fix something that’s not even a problem for you.
I’d just start using it the way it is before making changes, and when you do, make them incrementally as you discover how you use your system. Or wait until something is not working the way you think it should, or want it to, or more efficient, then make a change for that particular thing.
Here are two good reads as well:
https://forum.endeavouros.com/t/a-complete-idiots-guide-to-endeavour-os-maintenance-update-upgrade/25184
https://wiki.archlinux.org/title/System_maintenance