The APP partition is the first partition. Normal install places a lot of other partitions directly following this. If you were to put a larger partition in, then I think something would either be truncated or overrun. Failure is likely.
There is some ability in a GPT partition scheme to reorder labels so far as the number used with a partition, but I’m not sure if this could be applied in this case…very likely the larger partition would always fail.
You also want the other partitions to be from the same release, so for example you wouldn’t want to clone R27.1 rootfs and put it in an R28.2 pre-release.
If you cover a cloned raw partition file with loopback you can use gparted to manipulate the loopback device to resize your clone as if it were a real disk (you’d have to reduce it unless you are willing to pad the end of the file with NULL bytes first…then you could also increase the size…any pad would need to be a multiple of the block size…e.g., 512 bytes at a time for most disks).