To make it even more foolproof install Ventoy on the flash drive and then just copy the Gparted Live ISO on the drive. Ventoy will detect the ISO and let you boot it.
You can add other useful ISO like this and have them around. You can also make folders where you put other files you need and use the drive as a regular drive, Ventoy won’t mind.
But yeah, never modify partitions from the same system that runs on them, always boot into a separate flash drive.