a simple rule of thumb is if the enviroonement and temperature is suitable for you not too hot not too cold is aslo suitable for the cannabis plant to thrive.

over the years i have had seedling and first week of veg with as low as 20%rh and up to 80% rh most of the time i have around 50% usually, never noticed a difference in growth vigor depending the rh with proper watering pratice. then past flowering stretch i always strugle having lower than 50% rh, and i have had issue with mold with rh as low as 50% rarely with some phenos