What is the best humidity for my plants

hi all , I'm new to this. I hear a lot of different things are best for plants. But I do not know what to keep the humidity at. Plants are 21 days old and have 5 noids. And look great so far. I want to keep it that way. Thanks for any info.

60-65 with low 70s temps is what i like. No lower than 50 or higher than 70 i would say if you fluctuate.

I run 55% RH with temps in the low 70s.

40% the last two weeks.