How can I update a container every time it is (re)created?

I need to change an ARP record every time my containers are run, I can do this manually either in the container (if the container has NET_ADMIN and after installing net-tools) or via the host (with a script I've written) but I'd like it to be automatic.

I've tried adding a command to the compose but that doesn't seem to do anything (other than restart the container every few seconds), does anyone know how/if it can be done?

I think it would be better if it can be done automatically on the host but at this point either would be fine.

Does anyone have any ideas?

Thanks.