Tsushima's Phantom combat system makes a few people scratch their heads, unsure whether they can lock onto enemies or not. This is because Ghost of Tsushima is quite different from many other games you may have played. The locking system has become the most common way third-person action games track the action, especially in group fights.
How to lock enemies
In Ghost of Tsushima, developer Suckerpunch gave players a more subtle version of this system. When facing a group of enemies, a slight straight nudge at an enemy will focus your character's attention on that person. You will then be able to go around, advance towards or withdraw from that enemy depending on how you move.
There won't be a symbol on them pointing out that they are your goal, as the developers have gone for a very clear HUD, even in combat. To change enemies, all you need to do is gently push the right controller towards the new enemy you want to focus on. When you kill an enemy or start a fight against a group, you will automatically focus on the nearest enemy, so make sure which one you want to focus on next, and no, just select another enemy with the dial right.
This makes the combat more subtle and difficult in the game, as you need to be aware of your surroundings and enemy placement, and can't just use a system locking system to spam and stay locked. Instead, it's best to think a few steps forward in strikes, blocks, and throws, and always keep in mind who your next target will be when the current target is sent.