Even if you take it to Apple, a backup from your part is advisable and required, actually. Apple won't take responsibility if anything is lost.
For a backup, the best and more complete option is the one using a computer. It contains more info than the one made to iCloud (+ iCloud must have enough space in order to make a backup). You can see the difference between backup methods and how to make them here Backup methods for iPhone, iPad, and iPod touch - Apple Support
Please, always keep a backup on your computer, performing updates to those like every 2 or 3 days, maybe a week depending on how critical is your most recent data.
For your photos, the above method will save them all to your computer, but you can also get them all to iCloud Photos. See Set up and use iCloud Photos - Apple Support. You must also have enough space on iCloud for that.
Now, iCloud starts with a 5GB free option, bigger ones are a monthly payed service iCloud+ plans and pricing - Apple Support
About tech being simple, it is way more simple than it used to be, I guarantee you that. But there are a few things that remain a bit more complex just because they require some steps and configurations that can't be left aside.
For a factory reset, see this Restore your iPhone, iPad, or iPod to factory settings - Apple Support.
A clean install is a bit more complex, but if you want to know what it is (and you'll see it's not that hard), see this https://wccftech.com/how-to/clean-install-ios-15-ipados-15-final/ (the links provided in the article for iOS download are straight from Apple, so original files).
WARNING: don't do any of this without having made the complete backup I mentioned before, OK?