Generally, the same fish that go well in other tank sizes are also great for 55 gallon fish tanks. It just so happens that you can now keep more of them together with other fish.
Individual bettas can be added to community tanks and live in harmony with other fish, though you might run into the occasional betta that just wants to pick a fight with everything.
These exotic, gorgeous fish have a reputation for being difficult to keep alive so you may want to reconsider getting them if you’re relatively new to the hobby.
What works for one might not necessarily work for you. It’s time to stop trying to curate the perfect self-care routine and focus on improving one thing at a time.