The now 20-year-old actor joined the hit Netflix sci-fi series in the second season as Max Mayfield, a tomboyish newcomer who befriends the main group.
In a new interview with Fashion Magazine, Sink said that the casting directors were initially hesitant about her “old” age, despite her only being 14 at the time.
“I just begged and pleaded with them to give me more material so I could show them something fresh,” she recalled, adding that the role felt “right”.
In other recent Stranger Things news, Jamie Campbell Bower – who played season four monster Vecna – opened up about his battle with addiction in a tweet celebrating seven and a half years of sobriety.
Earlier this week, series writers also denied editing any scenes from previous seasons.
The response came after the co-creators of the Netflix show, brothers Matt and Ross Duffer, claimed that they had been editing past seasons – a move they called “George Lucas-ing”, referring to the Star Wars director’s habit of editing his films years after they’ve been released.
The first four seasons of Stranger Things are out now on Netflix.