I'm modeling for nearly a year in Blender but even with that times dedicated I can't find a way to model this parchment. Can someone give me some tips that I can use?
The difficulty is that it's a bas-relief. You can try it this way: Create a mesh with edge loops that follow the shape of your parchment:
Move some vertices forward to create the volumes:
Here is what it gives, of course you'll need to add a Subdivision Surface modifier and some support edge loops: