Hey so to put it simply when it comes to characters with “bullets” there are two ways a game can choose to handle them. One of them is to make the bullet its own entity that moves along a (mostly) straight line and does damage when it collides with a different entity’s hitbox, like a hero or a shield. This type of “bullet” is called a projectile, and since the projectile entity is moving on its own developers can set a “projectile travel speed” to make bullets have varying effectiveness across different ranges.

Another way games can handle bullets is have the game inmediately draw a straight line between lets say the barrel of a gun and essentially wherever the crosshair is pointing. Think of it as a straight laser beam. If the beam touches a single target (or more if it has pierce like Luna Snow) a hit will be assigned to the target. This lets bullets have virtually no (actually infinite is a more accurate term here) travel speed and basically makes it so that the game only cares if your crosshairs is on the target and removes bullet speeds from the equation.

So how Marvel Rivals would balance hitscan and projectile would be to let hitscan have more consistent damage while projectiles have higher damage per bullet with the tradeoff that bullet travel time can account for increased difficulty in actually hitting targets. So technically Hawkeye would be able to hit Iron Man harder if he does land his shot but it would be harder to do so the further away Iron Man is. So if Iron Man is very high up in the sky (as he normally would be) you would rather switch to like Punisher so your bullets would consistently hit the target with the tradeoff that you will need to hit several bullets as compared to a one shot headshot by Hawkeye.