My DD is eleven, and she had her friends also tend to get a bit shouty over video chats and whilst co-op gaming.
Like you, she's an only child and like you, this is her only social contact with anyone not an adult (or, indeed) a parent at the moment.
We do absolutely expect her to moderate her volume to a reasonable level during chats and games, when there's a reason for this. So, if we're in the room with her and she hits a volume which becomes unpleasant, or when she's a work with me and people are trying to concentrate. Failing to moderate after a warning does mean we ask her to end the chat, move to another room (if that's possible) or come off the game.
However, we also make a point of giving her times where we're NOT in the room and she has control. So, for example, she and some of her freinds now have a regular Sat evening gaming slot, where she has control of the lounge, and we move to another room. We would only moderate then if she got loud enough that she was causing a noise disturbance properly - i.e. there was a risk of our neighbour hearing it. We've never had that issue yet.
Children can and should be taught to moderate volume when needed - I can't stand the shrieky shouting that goes with the gaming - but at the current time, given it is her only social contact, it felt unfair to always having to be hushing or interrupting or asking her to cut it off, so we found a compromise.