Honestly, and I say this not to be rude but to make you understand - you totally need to educate yourself on the basics of using your operating system. You seem very lost in what even the most basic commands do or how to structure them, what the files in your filesystems are, what the different paths in your filesystem are, and which paths cover what (for example, / will cover ~ so if you back up / you don’t need to also back up ~)
So yes, the answer to your question is that you can just add / at the end of your backup command, but if you want to back up everything you can just replace the ~ with / instead since that’s the more proper representation of “everything”.
Note that you’ll probably want to exclude certain directories, there’s a lot of files that aren’t relevant to back up at all, e.g. some runtime and system files. There should be a bunch of topics about backing up (and I think also restoring) full Linux filesystems or similar, feel free to search a bit to perhaps find them. There’s a lot of people backing up their entire system.
The blessing in disguise isn’t so much due to an actual disguise, you should know that if you back up ~ this will not include /. There’s nothing disguised here at all
Apologies if you feel offended, but I’m just bringing up the elephant in the room. Hopefully for the best - if you continue like this it’s just a matter of time before you run into some really big problem or data loss or vulnerability due to not knowing how your system(s) work. Noone wants that to happen!