AFAIK, it's not recommended to play with Persist partition (incl. even restoring your own Persist backup) because you can loose some info specific to your device. I didn't play with but I've seen discussions about a year or two ago (unhappy users who complained about and about Xiaomi for that)
Anyway, with root, you can backup Persist through adb:
adb shell
su
dd if=/dev/block/bootdevice/by-name/persist of=/sdcard/persist.img
persist.img will be saved to Internal memory
To restore, replace the source (if=) with the target (of=) and vice versa
You can do the same through Terminal app, however without:
adb shell
Some versions of custom recoveries like special builds of TWRP, SHRP, BPRP, Orange Fox can opt you to flash persist.img to Persist, or they can even allow to choose Persist partition when taking Backup and Restore