How to make systemless edits to /system with Magisk

Many different root-only actions involve mounting and editing files in the Android /system directory. Because there have been so many types of Android OSes, rooting techniques, and actual root solutions from the last decade, it has made it difficult to confidently determine if this is possible with my current root solution: Magisk with locked bootloader. From my understanding, Magisk is a completely "systemless" root solution, so by simply disabling Magisk and rebooting, *all actions performed as root are reverted.* This is important for me because I have verified boot with a locked bootloader via [avbroot](https://github.com/chenxiaolong/avbroot/) , so if there is any change to the system partition then it will fail to boot and the device will be bricked. So, with Magisk, is there a specific module that is required in order to "write" to the system partition systemlessly, so that it's not actually changing anything in the real system directory? Or does Magisk do this by default, and all I have to do is make my file edits from a shell like ADB root or Termux su, and they will be applied systemlessly?