Stuart Williams, a voice actor, took his seat behind a microphone at a sound studio in Manhattan one cold day early this month. On a screen in front of him played a steamy love scene from the second season of “Bridgerton,” the hit romantic streaming series set in Regency-era London.

“He lies behind her, gently moving his hand between her thighs. Their lips remain pressed together as he shifts to lie over her, supporting his weight on his powerful arms,” Mr. Williams intoned in his crisp English accent. He went on to describe what else Viscount Anthony Bridgerton did with his hands and what his lover did in response.

After recording the take, Mr. Williams blushed deep red.

“It does feel sometimes like I’m reading from one of those grocery store smut novels with Fabio on the cover,” he says.