It doesn't take that much experimentation, though. Either set up not enough swap and keep increasing it by a little bit until you stop needing to increase it, or set up too much, and monitor your max use for a while (days/weeks), and then decrease it to a little more than the max you used.

I went with "set up 0 swap" and then never needed to increase it. I built my PC in 2023, when RAM prices were still reasonable, stuck 128GiB of ECC DDR5 in, and haven't run into any need for swap. Start with 0, turn on zswap, and if you don't have enough RAM then make a swap file & set it up as backing for zswap.