I suspect there is but I dont know about it (I use SmartOS / Triton). There is a small list of jail management tools [1]. If it doesnt exist it should be really easy to make since FreeBSD jails (usually) sit on ZFS you can easily use "ZFS send" to create a image of the ZFS dataset. All that one would need to add is some (minor) tooling.

On the more "heavy side" I know that for example Project Fifo has experimental FreeBSD support [2] in case you want to host multiple FreeBSD machines with jails on them.

[1] https://mwl.io/archives/2291 [2] https://docs.project-fifo.net/docs/freebsd