I don't know if this is the case but trying to export RCS images is so difficult It takes up space on android phones and I don't know how to backup completely

I don't know if this is the case but trying to export RCS images is so difficult It takes up space on android phones and I don't know how to backup completely and then remove To be fair, same for iphones, when I help my family/relatives, I can use Google photos to export then delete photos but don't know what to do for imessage