It would be extremely useful to have the ability to change the pen size, this way if we are creating a title and we want it to be bold and big, we can do that or if we want our writing to look thicker, we will also be able to do that.

To adjust sizes, you could ether have a like dot that you move left or right to increase/decrease size (example below)
OR
Have options for varied sizes e.g. 0.5 0.7 ....... (LIKE PEN SIZES IRL)