Hello, I am thinking of starting a website about hairstyles or hair care. My request to those who have sites in these categories: what is the traffic like, what are the AdSense RPM rates, could you inform me? And of course, how is the competition level?
I can’t speak for Turkish, but it’s hard to succeed with foreign content.
I opened one too, didn’t add much content, it gets 10-15 hits, and I couldn’t put ads on it because I don’t have AdSense 
If you are going to open one, you should pay attention to the traffic coming from Google Images, because mine usually comes from there 
If you’re not a fashion designer or something, you won’t get too attached; you’ll drop the site after a while.
It is a highly saturated category both in the Turkish and global contexts. Sure, you will earn something, but you put in a lot of effort for very little return. Instead, consider niche websites where fewer people compete and where you can rent ad spaces to businesses outside of AdSense. For example, you can focus on the keyword “Bursa wedding hall”, rank for this low-competition keyword, reach out to wedding halls, and rent out the ad space.