I believe you’d be looking for a Height Blended Material (for this part at least), probably using a Height Lerp node? Take the output of height lerp and use it to apply beach to low areas, another height lerp to get high areas, etc.
If you made this terrain with a terrain gen program, you could also export masks for each height level, for example a “low mask” that shows all low areas, and use that mask to apply the texture you want in the masked areas.