oh i just use noise textures i’ve made from scratch! in Photoshop you can make them by making a flat color layer and then going to [Filter] -> [Noise] -> [Add Noise] then play with the settings however you like.
in Clip Studio Paint, you can also make your own noise texture. same procedure as Photoshop but go to [Filter] -> [Render] -> [Perlin Noise…] and set the Scale % to 1.00 (or however you like)
after i’ve made the texture, i usually set it on Soft Light or Overlay depending on how intense i want it to be. lower the Opacity % as how you see fit.
