That's double speak.
It’s not - if you’ve ever gone to churches and listened to pastors speak (not from their own authority, as they say). And it’s not when you go to seminaries and are taught about the doctrine of God’s Word and that being the authority.
I’m afraid this indicates you’re basically unfamiliar with this idea and theology - which is the theological doctrine in every Evangelical church that I’ve ever been in - in my entire life.
I’ve NEVER ONCE heard a pastor speak as if he’s speaking from “his own authority” - but ALWAYS - speaking from what God’s Word says, and he quotes it and goes into the understanding - usually from the ORIGINAL LANGUAGE itself - and if necessary, giving quotes from those who are experts in the original language and explaining exactly what the wording and syntax means - in that original language that God gave to us. And they all say that God’s Word is exact and precise (and that’s what it says “of itself” too) - down to the very sentences and words.