I’m not that familiar yet with docker compose, but I think it should be something like this.
command: --operator.wallet-features="zksync"
The point of this would be to add this argument to the entry point of the docker container. I believe this should do just that.
You can check the web dashboard to see if it works. It should say zksync opted in next to your wallet address. If this isn’t it, best wait for someone with more experience with docker compose.