Substantiated… anywhere else, I assume? You’re pointing out what’s correct: that we don’t need to assume that God created the universe, because the Bible does teach it, in that beautiful first line. I don’t know how much chasing down you did, but here’s more for you:
This is what the LORD says: “Heaven is my throne, and the earth is my footstool. Where is the house you will build for me? Where will my resting place be? Has not my hand made all these things, and so they came into being?” declares the LORD (Isaiah 66:1,2).
All things were made by him, and without him nothing was made that was made (John 1:3).
For by him all things were created that are in heaven and that are on earth, visible and invisible, whether thrones or dominions or principalities or powers. All things were created through him and for him (Colossians 1:16).
By faith we understand that the worlds were framed by the word of God, so that the things which are seen were not made of things which are visible (Hebrews 11:3).
For he chose us in him before the creation of the world to be holy and blameless in his sight. (Ephesians 1:4).
This last one is about God the Son, and how the God the Father chose him before the creation of the world, obviously implying that they were both present at creation — and unless someone else was there to do the creating, they’re the ones.
Two things to note: I haven’t spent a ton of time trying to understand and explain the Trinity, so if you have questions there, I won’t be your best resource. But plenty of very astute theologians have studied and taught/wrote/spoken on the subject, if you want to chase that line.
And second, you only asked for Bible verses to support the premise, not any further evidence; so that’s all I’ve given, but there is extra-biblical evidence that can and has been offered, as I’m sure you’re aware.