How do you stop TimeMachine from erasing a disk you're transferring your backup to when you go to select the new drive in Preferences?

I've been looking around how to transfer a TimeMachine backup folder to a larger external USB HD. Preferably I'd like to use the method that Apple recommends in this article https://support.apple.com/en-us/HT202380 (I'm aware that there are other methods, DiskUtility cloning and CCC cloning, but I'd prefer the method recommended by the system designer). However, even if I were to select any other option of copying the files over to the new drive, I still run into the same problem. How do I stop my system from erasing whichever drive it hasn't backed up to before (as I'd assume the system keeps track of the physical drive address or device number to know which drive it's storing its files in), especially when I'm trying to retain the TimeMachine backup files that I've copied over to it?

Side note, I've also attempted to copy the folder over after I've made the drive into a TimeMachine drive; however, in BigSur, the backup drive is now formated into APFS, and you need to make an entirely new partition container for any data to be stored other than the backup. And then I feel I'd run into the same issue.