Reduce space allocated to Photos

Hi, Is there a way to limit the amount of storage utilised for photos/videos? I have a 128GB iPhone 13 and 97GB is taken up by photos. In total I have approx 28,000 photos.

And before you ask -

Yes, iCloud backup and photos is on

Yes, Optimise Storage is on

Yes, I've tried running manage storage

The iPhone keeps locking up as there is no free space yet its not automagically offloading the excessive amount of photos it must be storing locally.

I thought perhaps I could disconnect iCloud photos on the device and choose - remove from device, and then reenable it later (I don't want to mess with manually grabbing photos off the phone with image capture or Photos on my mac..).

Why isn't it working? Ideas?

Thanks