How to build arched outdoor plant support
I found some that were created by Hometalk members. Hopefully one of these will inspire you to create the one that fits the area where you need it. Wishing you the best.
You could use an arched vinyl lattice. Put up your posts and arch the lattice and nail it to the posts. That would be the easiest way and you could choose how deep you want the arch or small by cutting off what is excess.
This might help: https://www.hometalk.com/1367206/making-a-woven-trellis