This guide will let you know how to fight in GTA 5.
The first thing you will need to do is get closer to the character you want to fight with and press the left click button on your mouse to hit him. Keep hitting the click button to kill him.
If you want to hit anyone with your elbow, start the fight and turn back. He will follow you and come closer; then, you can press the left click button to hit him with your elbow.
You can also hit other characters with the gun. Just equip the gun and aim at them using the right-click button. Then press the left click button to fire.
The next method to attack is using a knife. Equip a knife, get close to the character and press the left click button to strike.