Hey c/Selfhosting, I'm finally dipping my toes into creating a NAS for my household, after saving up funds for awhile. Hopefully this is an okay place to ask a dumb question:

Is it possible to gradually add drives to a NAS while maintaining a RAID array?

I'm about to pull the trigger on an aoostar WTR Pro (4 bay), but budget will only allow for 2x 4tb drives to start off with. I'm wanting to do RAID1 for data redundancy, but eventually I'd want to add another 2x 4tb drives to get to 8tb of RAID1. Is this possible without having to copy out all the data from the NAS? Would I have to start the initial setup as RAID10 instead of RAID1? I wouldn't mind doing trial and error with it if storage wasn't so expensive down here in NZ, and the whole household's data is going to be on it. Thanks for any guidance in advance

Context: Currently the plan is to either go with the 4 bay or 2 bay R1 pro with the Intel N150, install TrueNAS, Immich and Jellyfin, pretty lightweight stuff (I hope). Trying to keep it around NZD1000.