gpart is not actively maintained, it is a legacy program (still useful to find partition info or file systems that don’t show up when you think they should, as it ignores any info already there and just searches, *BUT this also means it will simply ovewrwrite anything there if you were to issue commands like that you show in your post!)
If you want a command line option for partitioning and formatting, use fdisk to create partition structures and mkfs to create file systems on those partitions. They are part of the util-linux package and should be on your system already;