There’s plenty to read up on but I think starting with any is a good place. You’ll find stuff you dislike. I’d recommend setting up ventoy on a USB (it will let you have several linux images on one thumb drive) and testing out most importantly the desktop environment (DE).
Main ones being KDE, GNOME, and cinnamon that comes with Mint (which is a great first distro to test).
If you end up having questions feel free to DM me
As a user you can’t access the filesystem. It’s completely abstracted away. At least this was the case for the iPhone 6