It's interesting looking at this motherboard VRM tier list:
Credit to: @LukeSavenije The following list is based on facts, ranked on power delivery and known problems. The list will include boards that support CPU overclocking available at retail from different brands. There are still differences in performance among boards of the same tier. As a result, ...
linustechtips.com
It looks like with Zen 3, you can get away with a 100 amp board for a 5800X, and a 125 amp board for a 5900X (apparently that's enough to max them out).
Still, maybe worth spending a bit more to get something like a Gigabyte B550M Aurus Elite or Pro.
It's a shame there's no equivalent VRM lists for Intel boards, showing their maximum current draw.