Do you mean the project size (CPR file) or do you mean the whole Project folder? If you apply any Direct Offline Process, new audio file is generated. So in your case 5 new Audio files (96kHz) has been created, therefore the size (of the whole folder) increases.
Yes, the whole project folder - after a second look, I realized the edited audio files were duplicates, or “new” edited files - how would you properly manage this if, say, you had used offline processing on 20 or 30 audio files?.. delete the originals, or?
No let them be, that is your only option if you want to undo anything later.
When it gets too big, use the backup function in Cubase to produce a clean new project in a different folder, and archive or delete the old one.