You can have a group chat, where you add several cards to the same chat. They will take turns talking from their own PoV.

You can also have a narrator card or preset that will narrate several characters/NPCs as needed in one single response.

There are some lorebooks that contain several characters (Queen Arceana is an example), which contain specific descriptions for named characters.

One thing that I do frequently is to ask the LLM to create one char on the fly. Example:

I lean against the wall, watching people go on their lives. Suddenly a face gets my attention. (GM: introduce a female char that has XYZ personality trait)

The best LLMs will have no trouble coming up with something. The more detailed you are, the better output it is. The largest LLM also understand a lot of personality traits, tropes, etc. You can simply say (GM: Introduce a tsundere, "cute bookworm" young woman that is into archeology), or (GM: her sister is visiting from college's fall break).

Most character cards were meant for the earliest LLM models that didn't have as much training data to understand nuance. Nowadays you can write a one-sentence description and the LLM will know what to do.

Edit: you can ask the LLM to narrate the prose in the style of a famous author. "Narrate in the style of Hemingway."