My bad, I guess that isn't an option in AMD 5000 series.
On to undervolting!
THIS IS A SAMPLE SCREEN FROM AMD, NOT NECESSARILY FROM A RX5700
Best just to enter the new voltage values numerically in the boxes. Try subtracting 50 from each of your stock voltage values and test stability (and clock speed)
You can also enable "Power Tuning" (right side of screen above) and increase the power limit above 100%. Increasing the power limit does just that, it allows the GPU to pull >100% of the stock power limit. It's
better to undervolt first (which reduces power draw, hence heat and noise also). If the stock limit is 180W and you're hitting that limit before...