Will a sprained ankle ever heal 100%?

Usually heals. For residual pain after a sprained ankle an evaluation for a osteochondral talar dome fracture is needed. Mri or ankle arthroscopy may help.
Not all spaghetti . Is the same. Some ankle sprains are little nothings that need no treatment and heal in a day or two. Other ankle sprains are really torn ligaments which can leave the patient with a lifetime of problems. So, to answer your question, it all depends on the severity of the "sprain.".