Just a hard round brush around size 70 or 80, but at the top toolbar when you pick the brush you will see the 3 pen adjustments. The buttons look like an pen making ripples in water. Or an arrow hitting a target. One is for Opacity, one for flow, and the third for pen pressure on and off.
So from left to right
1. Turn on Opacity and pen pressure
2 Same settings
3 Turn off Opacity
4 Turn on Opacity and go to brush settings should be on the right side panel and set spacing to like 30 to get the circle effect
Hard to remember, I switched to Clip Studio Paint. Just preference I like it more for doing comic art.