[Question] what is the recommended procedure for replacing a pool on TrueNAS?

I bought some new drives to replace the old ones I had lying around, and want to replace them entirely (4x 1tb -> 2x 4tb). I have a few apps running on it (Syncthing, Transmission, Tailscale, etc.), and I wanted to know what the best way to perform a drive upgrade would be. AFAIK the apps are installed on the pool as well, so...