Depends. My old unit is the alert unit for that very thing. I spent 6 years training in nothing but riot control during AT. It’s usually a multi tier system. Front line, shields, masks and batons. Second line Had the same but was equipped pepper ball and CS. Third line has batons, but had weapons at the ready, 4th line was usually vehicle mounted with a variety of non lethal and lethal systems.
Best marksmen were the ones equipped for lethal action. Incident Commander alone could give the order. And depending on the RoE, if fired upon, we could or we could not automatically return fire without the ICs order. As a team leader, and an expert marksman, I was in the 4th line in a turret the latter part of those 6 years. First 2-3, I was in the front line
Luckily, I never had to find out what it’s like to stand there. But we trained like hell, even had role players to throw **** at us during some of it