If you want something more turn-key, go for a Synology box. Go for something with at least 2 drives like a DS220j for less than $200 or the slightly better DS223 for about $250. Just pop whatever drives you want in there, I’d suggest server-grade, NAS drives or SSD for better reliability. Setting this up to work with Time Machine is very easy and there are tons of walkthroughs online for setting that up.
For a more DIY approach, you can build a TrueNAS box (formerly FreeNAS). Tons of tutorials you can follow online that will tell you everything you need to go this route.
One thing to note, a NAS will only be available on your home network without additional configuration. TailScale is my recommendation if this is something you want to do.