In my RX6750XT's case you can get ~97% of the max performance with tuning max clocks to 2,6GHz and voltage to 1,175V which results in 1,05V max and limits the power draw from 210W to ~170W (the power figure that AMD reveals through the sensors).
This 1,05V is an absolute max limit the goes only lower depending on the load. In another tune I tested and which retains close to 90% of the max performance, the 1,125V for 2,3GHz in the driver suite resulted in a 0,97V max limit that lowered the power draw to 110W max.
Maybe the 6nm helped in efficiency but I suspect that most RX6700XTs will be close to that.