Is the Trinity in the Book of Isaiah?

Isaiah is one is the main prophetic books in the Bible, and is quoted in the New Testament more often than any other Old Testament book, except for Psalms. Is the Trinity doctrine in the book of Isaiah?
THE TRINITY ASSERTED TO BE IN ISAIAH
“A cornerstone belief of the Christian faith, the doctrine of the Trinity . . . What is the doctrine of the Trinity? . . . There is only one God, but in the unity of the Godhead there are three eternal, coequal Persons where each Person is independently conscious and self-directing but never acting independently of one another and always manifesting the same character attributes and the same nature. Where in the Bible is the Trinity taught? . . . It is taught in 25 of the 27 books of the New Testament and in 13 of the 39 books of the Old Testament”—“Does the Book of Isaiah Teach the Trinity?”, Reasons to Believe (RTB) blogsite, by Hugh Ross, July 20, 2020



is true. However, the Trinity doctrine goes far beyond acknowledging the existence of God, Jesus, and the Holy Spirit. What exactly is the Trinity doctrine?