[dominicperry]

Unfortunately you need to compare an M1/M2 machine with your workload to be sure. Using an Intel machine won't be as accurate.

In my opinion, the best way to do this is either:
1) max out the memory, regardless.
2) Look at Activity Monitor. Click on the memory tab and look at the Memory Pressure Graph and the amount of swap used.
If memory pressure is anything bigger than a little trickle at the bottom, you could do with more memory. If memory pressure is yellow, you could really do with more. If it's red, you need more memory.
If swap is a large number, (more than a few GB) you could usefully use more memory.
Check these things while you have everything running that you will reasonably expect to have running.

I have 64GB of memory. Memory Pressure is 4%. Swap is 0 bytes. Compressed is 0 bytes. That's how I like it. (I don't think "Cached" is particularly pertinent as it just gets flushed if the space is needed for something else).

Dominic