How to make a full backup and restore (including ROM) using Windows PC via USB?
Flash (or temporarily boot) a custom recovery like TWRP, and you'll be able to make a Nandroid backup. It typically includes the boot image, the system image and your internal data (excluding Pictures, Musics, Downloads etc.).

When you restore a Nandroid backup, everything goes back to the exact state before the backup.

You won't be able to back up the boot image and the system image easily otherwise.

You can read more at the tag wiki of our nandroid tag.

Note: Even booting temporarily into TWRP requires an unlocked bootloader (if it's previously locked). If you haven't previously unlocked it, be aware that doing so wipes out all data on your phone, including your internal storage where your pictures, musics and downloads reside.