iCloud's built in applications take up far too much device storage even in the 'optimised' mode

Despite the fact that I have everything saved to iCloud, the built-in applications insist on taking up gigabytes of storage (collectively around 15 GB just from Notes, Mail and Photos) despite me having everything on Optimise Storage and running out of on-device storage. I understand why the device would want to keep some stuff downloaded, but the options to control this are either non-existent or extremely limited. I use Notes a lot - I use it to do assignments on my Macbook, scan documents in, make actual notes, write stories. All in one place. Photos is self explanatory. And Mail... I don't even know why it needs to take 2 GB. Everything is stored on iCloud, between the 3 devices linked to my account. And yet, it downloads 15 GB of data which I have no way to remove, aside from disconnecting those apps entirely from iCloud, which A. will likely leave everything downloaded anyway and B. I use all 3 devices almost equally and therefore I am not going to stop syncing files between them. I have tried deleting and reinstalling Notes, but it made little difference as my frequent use of the app led to it quickly redownloading everything every chance it got. The above applies for Photos as well, and, as already stated, I simply don't understand why Mail takes this amount of space. I would really appreciate a way to increase the optimisation (similarly to how Music works) so that it will remove unused local files. I use Scan Documents a lot, so perhaps an option to have these images stored ONLY on iCloud would help alleviate the storage issue. As for Photos, once again, if 'optimisation of storage' is leaving 5 GB of photos on each of my devices despite having the full files in a 2 TB iCloud storage anyway, then it needs improvements. Same goes for Mail; store older emails and images on iCloud, and just iCloud, to be downloaded as necessary. You can't use Mail without the internet so I don't understand why there's no option to not keep older Mail messages downloaded to the device. iCloud files can be accessed on the website (as long as that feature is on, which, for me, it is), so couldn't it be implemented like that in the apps instead of downloading 'smaller' versions of everything that I've stored on iCloud, a storage system made for the purpose of helping you not have to store things on-device, to each of my devices anyway? Notes is taking up less space on iCloud than it is on each of my devices by 3 whole gigabytes, and I really don't understand why this is necessary considering my iPhone has acknowledged its lack of storage space anyway. Surely that should mean Notes on my iPhone could offload some older files it doesn't need?