Video editing/post production is resource intensive.
Whilst DaVinci Resolve will work on any current Mac, it is, at heart it is a high powered program, and needs a certain level of resources to be responsive. It is handling multi-stream video/audio, processing it, and refreshing the interface constantly.
Because of this if your projects have any degree complexity there are huge advantages to having the immediate work-in-progress files all stored on the internal SSD.
Project files, render caches, 'undo' files, immediate backup files etc.
So for anything other than Tic-Tok length projects it it best to have at least 1TB of internal storage.
Everything else can be on external storage, and you can transfer stuff off the internal as soon as it is not in immediate use.
However for getting started, the lowest level Macs are now quite capable of handling 'beginner' productions.
So it's your choice as to how far you want to go...
Others will have to advise on animation software.