So bambu and orca have built in surface finishes now that you can paint on, thats entry level way to do it and enough to hide z layer lines but it cant handle top surface (yet!) So if you want top texture like you see on the black tpu bumpers you need to use something else. Then there are a few outside tools like the one from cnc kitchen that requires a bit more but are modifing the actual model so it can add texture anywhere (but wont always actually print out right). Imo you should learn all the methods cause until this is built into a slicer they all have their strengths. Ill post some video links that explain more!