Psalm 27 speaks of trouble David experienced with enemies, adversaries, false witnesses and violent men.
There is such a marked change between the first half and the second half of this psalm that many suggest that it was two different psalms stitched together.
Pastor David Guzik also gives three ways Psalm 27 points to Jesus.
Here is a link to David Guzik's commentary on Psalm 27: https://enduringword.com/bible-commentary/psalm-27/