Hi, it's already been done, just not the way you might expect. Capacity of street-side stops is limited by the size (area) of the sidewalk, so that the passengers have room to wait. It's hard-coded into the game that way. So the only way to increase the capacity is to make the sidewalks wider, which some modders have done.

Here's one I use that includes a bunch of streets with wider sidewalks:
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2557053030

I think this one does too, but I haven't tried it:
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2557057425

This can help in some cases but it still has limits. The expectation is that you improve your line rate with more/faster/larger buses when a stop becomes so crowded, or switch to using a bus station instead. You shouldn't need 180 people waiting around a street stop to board the same bus lol.