Font relative sizes

Hi all !

I've recently been experimenting with fonts. I've been reading in Times New Roman for years, and recently tried bookerly (I'm loving those italics !)

I noticed, tho, that when switch from one to the other, the text size varies by a lot. I usually go for about 20 to 22 lines per page, but when going from times to bookerly i need to scale font down by 4 or 5 notches to get a similar size.

Is there a way to specify some sort of "factor" or "base size" for each font ?