Common problem. Trust me on that.
Take a walk. Get away from your computer and stop staring at that dratted screen.
While walking and enjoying the weather and the trees and the beautiful birds overhead, think about your story. Dig deeper. Get inside the head of each and every protagonist in that fight scene.
What are they thinking? Why are they fighting? Do they really care? Let your mind wander and come up with whatever rises to the surface of your thoughts and don’t question your thoughts, just go with them.
Then, when you return to that dratted computer, remember your thoughts and you’ll probably discover that you have a lot more to say because you know your characters in that specific scene much better than you did before.
Maybe you’ll now describe more action because you’ll know what kind of action your protagonists might engage in. Maybe you’ll slip in some mini-flashbacks here and there to tell your reader why and how they are doing what they are doing.
Or something else that I can’t even imagine but that you can.