If that verse “proclaims Sola Scriptura” then what of God’s word that is not in the Scriptures?
He has revealed as much of Himself in the Scriptures as He has chosen to do. Much of His will and so forth are beyond our capability, it would be fruitless to ponder (last few chapters of Job come to mind).
If any man speak as a prophet of God, let his words be examined to see if they line up with the Scriptures. Because every man is liar and only God is True.