Check out ‘image’ software. They can make a bit-by-bit or contextual [used space] image of your hard drive(s). These kinds of programs are useful if you lose your OS drive. They have saved me several times over the last decade.
There are several image software programs available, and some have free-for-home-use versions.
I currently use Macrium Reflect.
https://www.macrium.com/reflectfree
I also partition my large hard drive to set my programs and OS on C: and data on D: partition. And of course, back up essential data occasionally to an external USB hard drive.
Macrium is good software.