“As soon as Jesus was baptized, He went up out of the water. Suddenly the heavens were opened, and he saw the Spirit of God descending like a dove and resting on Him. And a voice from heaven said, “This is My beloved Son, in whom I am well pleased!” Matthew 3:16-17 BSB
"Behold, My Servant, whom I uphold; My chosen one in whom My soul delights. I have put My Spirit upon Him; He will bring forth justice to the nations.” Isaiah 42:1 NASB
According to Isaiah, God the Father put His own Spirit upon the Messiah (“I have put My Spirit upon him” – Isaiah 42:1). Here we see that only One true God the Father spoke from heaven while His own omnipresent Spirit descended like a dove upon the man Christ Jesus. Thus we only see One Divine Person speaking and descending from heaven upon one human person. For God’s Divine Person (“My Soul” = One Divine Person in Isaiah 42:1) also became one human person via incarnation through the virgin (Heb. 1:3 “who is the brightness of His glory and the express image of His Person,” i.e. The Father’s Divine Person became a human person). Nothing in this text shows three coequal God Persons at Christ’s baptism as we see only “One God and one mediator between God and men, the man Christ Jesus (1 Tim. 2:5).” For the One Divine Person called the Father also became a true man person as the Son within the virgin (Matthew 1:20; Hebrews 1:5; Hebrews 2:17).
Trinitarian scholars allege that a Heavenly God the Son Person was both in heaven and on earth at the same time (John 3:13). Wherefore, just as an alleged omnipresent heavenly God the Son Person would be able to speak in heaven while simultaneously existing on the earth as a man, so our heavenly Father could speak in heaven and on earth simultaneously while being incarnated as a human person at the same time. If Trinitarian theologians can think of an alleged omnipresent Son speaking and acting in heaven while He was on earth, then it is not impossible to believe that the Father could speak in heaven while speaking and acting independently on earth via His human incarnation in Christ (John 14:7-10, 24). With man this is impossible but not with the Almighty and omnipresent God.