Before I reset iphone to factory...

I have an iphone 8plus and 3 ipads. I am mostly homebound with poor vision. I use the ipads daily in various rooms. They are 2 iPad pros (2017) and one iPad pro (2021). I don't use them for calls, just iMessage and email. Plus numerous app activity, many synced to cloud. They are all set to Auto back up and all three backups combined are taking up 23GB on icloud.

When I check icloud storage from my ipads it shows that iMessage accounts for about 14GB of the 23GB. Which is fine by me. I want to keep the iMessage history. That's not the problem.

The problem is my older iphone 8plus. I use it maybe 2-3 times a month when in a doctor waiting room. It's my hot spot for my ipad. I don't make calls on it (we have a home phone for that) and it stays on silent DND as I never accept calls. Calls to my iphone are not sent to my ipads. Only spam calls come in and I clear them out every few months. However iMessage is turned on as is Mail so I can get them using my pads.

I have never backed up my iphone because there's nothing on it that I need. But my family keeps telling me I should!! I tried backing it up once but it takes up 14.8 GB of my icloud which puts me at 48GB. And my plan is only 50GB.

I haven't a clue why my iphone is so bloated. As I said, it only has the basic apple iOS installed apps. I turned off the icloud app sync for the apps (except iMessage). I don't use the iphone camera and there's only 3 photos on it. I don't use apple music or anything other than iMessage (14 GB) and the hot spot. I've deleted all but 14 of the "apple apps" that are installed with iOS. So I guess the next step is to do a factory reset. (My daughter did a factory reset for me back in 2017 but she now lives in another state.)

So this is the scary part. It seems that somehow Apple has decided that my iphone is now critical to my Apple Account. Around 2020, Apple began sending some sort of code to my iphone and I have to confirm that code on my ipads or my MacBook when I sign in or out of my apple account.

So if I do a factory iPhone reset, is that going to cause a problem to my apple account? I couldn't add my 2021 ipad or my 2020 MacBook unless I entered the code sent to my phone. If I do a factory reset, does it know that my iphone and number still belong to me? Will it mess up anything on my apple account in regards to verifying it's me?

I've read to first back it up using iTunes or iCloud but since there isn't anything on the iphone that is important is there any reason to back it up? Wouldn't using the backup to "restore" my iphone from "factory" just restore the 14.8 GB that I am trying to get rid of?

Some things I have read say that the iphone iOS takes up a good 12-14GB. If that's true, I don't see any point in doing a factory reset.

My ipads come in at under 8GB each including iOS and app data storage. I find it strange that the iphone iOS uses so much more storage than the ipads running the same iOS (ver 16). Especially since the ipads also have like hundreds of apps and app data.

So is 14gb a "normal" amount for a seldom used iPhone? Or is it bloated?