One of the most obvious examples of the Trinity is in Mathew 3:13-17
The Baptism of Jesus
13 Then Jesus arrived from Galilee at the Jordan coming to John, to be baptized by him.
14 But John tried to prevent Him, saying, “I have need to be baptized by You, and do You come to me?”
15 But Jesus answering said to him, “Permit it at this time; for in this way it is fitting for us to fulfill all righteousness.” Then he permitted Him.
16 After being baptized, Jesus came up immediately from the water; and behold, the heavens were opened, and he saw the Spirit of God descending as a dove and lighting on Him,
17 and behold, a voice out of the heavens said, “This is My beloved Son, in whom I am well-pleased.”
In the creation narrative it talks about man being made in God's image where it says Let us make man in our image. -Genesis 1:26