To do this you need to increase pixel width (Or height) + do regional prompting for each character. Most of the time if the model won't do something simple that you ask of it, it just wants more pixels. For this one I had to find a lucky seed and do a lot of editing (Because they tend to clip into each others regional prompting boxes, and this is the max width I can make with the vram I have). If they are "close up" they will be more realistic but you have less possible characters like in this one, if they are "far away" you can have more characters but it will look less realistic.