Can we free up storage in iPhone

You can delete pictures, downloaded movies from streaming services or if you have downloaded music locally from, for example, Apple Music. You can also offload downloaded files from iCloud Drive in the Files app. The files will stay in iCloud, but will be removed locally from your iPhone.

You can find more useful information here:

If you need more space for an update on your iPhone, iPad, or iPod touch - Apple Support

You can free up storage by deleting photos, videos, songs and files.