Save files even in previous games always seem to bloat after some time of the same file, so I always end up making a new one eventually. Any sims that's been progressing through their generations and what not I always save to my library so I can place them in a new save.
Though, if I'm sticking with a save for a long time I usually tend to clear out my folder to get rid of the bloat.
-Delete the cache files in Sims 4 folder
-Clear out a sims personal inventory
-Got rid of a bunch of townies that aren't all that important
I always like to back up my game files and chuck them into another folder.