Plans for Hosting

Hello,
Sorry for my bad words. I’m a french newbie.
I’m on an OneShot deal : 1 website for 1 client. He already have an hosting solution and his own custom domain.
I’m thinking to build it via webflow Core Workspace, and then export the html code.
How the code would be edited in wordpress builder or in webflow in the future ? If I downgrade my plan from Core to Free after publishing, will I be able to reload this site in my DashBoard ?
Thanks for your help