God the Father with Israel in plan and purpose. In the following verse below, the words, "He has visited... His people" doesn't mean God floated down from heaven. And it is also clear that it means God the Father has visited His people since it as the Father who raised up this horn of salvation - Jesus.

“Blessed be the Lord God of Israel,
For He has visited us and accomplished redemption for His people,
And He has raised up a horn of salvation for us
In the house of David His servant."
Luke 1:68-69.

God the Father raised up Jesus, a horn of salvation in the house of David, and this is how God visited his people. Similar idea at Matthew 1:23. The way God the Father was with Israel is by proving them with Jesus to save them from their sins which is precisely what Matthew 1:21-23 says.

Also see Luke 7:16 for the same concept again.