Renting a Server, how much ram?

I want to start my own server, just for my personal usage, maybe from time to time a second person will join but mostly it will just be "single player" on an online server.

Its gonna be a Paper Server with the newest java game version 1.21.4.

After some research most people say 2-3gb is fine for 1-4 people, but this differs all the time, sometimes people even recommend up to 8gb.

It should just be a smooth experience with mostly no lags and a high viewing distance. So if i want to travel 10k blocks in one direction this should be possible without having server warnings all the time, or even worse crashes just because new chunks are generated. Same with redstone builds, i don't want to get panic everytime i build a redstone clock or use a little bit too much of redstone stuff.

So how much ram is enough for a smooth experience even after like 6 months of playing all day?