In what sense did Father dwell in Jesus? Is it a figure of speech?
It most certainly is not a figure of speech!
To entertain such a notion is to misunderstand the nature of Jesus entirely. I cast no aspersions on the OP as, no doubt, this was intended as a rhetorical comment.
Hold to the Rod said, "the Father is not physically present". But, that is precisely the point. The Father is 'physically' present as He could ever be - in Jesus. The whole "God with us' (Immanuel) is this precisely.
The Father is spirit and invisible. He has shown a measure of Himself in various ways, but this is now the most authentic presence of Himself - in Jesus.
"I and the Father are one"... same deal. Jesus is the embodiment - the logos/word of God here with them. Now, this is still true though it is by the Holy Spirit in us sent from the Father and Jesus.
Yes, Jesus is the son of God. He is on the same page as the Father in all things, having the same nature of love and outgoing concern, not inward focused and prideful. (Yet still with his own will)
But Jesus IS the very word, the intent, the purpose, the reason, the wisdom of God in a flesh form. This is not something to gloss over in passing.
So will My word be which goes out of My mouth; It will not return to Me empty, Without accomplishing what I desire, And without succeeding in the purpose for which I sent it. Isaiah 55:11
Who's word goes out? God's. The same God who arranged for Mary to become pregnant, the same God who John speaks of, His word became flesh.
Anyone who has seen me has seen the Father. How can you say, ‘Show us the Father’? 10 Don’t you believe that I am in the Father, and that the Father is in me? The words I say to you I do not speak on my own authority. Rather, it is the Father, living in me, who is doing his work John 14:9
The logos/word of God - God's word goes out to accomplish - God is in Jesus, His word, to accomplish His work. Jesus does or says nothing of himself - why?
Because he is the word of God - the word does not act independently - it is God's word - Jesus is God's word and does his Father's bidding - yet still with his own will.
That's why this is a grand new adventure - not just a 'word' that goes out according to plan to do God's will - but a man who now chooses to do God's will - against his own will on several significant moments. John 6:38
Jesus is not choosing to not be God, he is not choosing to be a man, he is not choosing to not exercise some inherent cosmic power. He has none - only what the Father gives him.
He told the disciples over and over in different ways, that the Father is his provider,
Don’t you realize that I could ask my Father for thousands of angels to protect us, and he would send them instantly? Matt 26:53
All Jesus' provisions and needs are from the Father. All Jesus had was a sinless, and therefore, holy beginning. The rest was God at work in him. Providing His spirit at Jesus' baptism, filling him with this essential connection with the Father prior to his battle with the devil. This spirit gave Jesus the words, the attitude, the wisdom, the miracles and through consistent prayer, the will to accomplish his mission - get to the cross without error.
Paul reminds us of an important truth.
for it is God who is at work in you, both to desire and to work for His good pleasure. Phil 2:13
Notice it is both the desire or will and the ability or work. All comes from God for us, just as it did for Jesus. We are privileged to choose to accept His presence in us and allow our nature to be aligned with His. This too is what Jesus did as he submitted his will to the Father's even though it got pretty tough toward the end.
Jesus life was a series of learning moments - getting him ready for the ultimate test of loyalty, of trust, of love. These are the things that he had to choose against his own will that thought there must be another way.
Although He was a Son, He learned obedience from the things which He suffered. 9 And having been perfected, He became the source of eternal salvation for all those who obey Him Heb 5:8
Jesus had the Father dwelling in him - just as he and God dwell in us through God's Spirit. This made him one with the Father - one in intention, purpose and love - yet Jesus still had to fight the temptation of this world and its leader to always serve God and never himself.
My Father will love them, and we will come to them and make our home with them. John 14:23
The Father was in Jesus in every conceivable sense because without this provision and relationship, Jesus would have failed as Heb 5:7 points out.