Question: it 2 what is richie's secret?
Answer: In the film, it is more than hinted that Richie, played as an adult by Bill Hader and as a youth by Finn Wolfhard, has a "secret" (something Pennywise threatens him with): that he has an attraction to Eddie Kaspbrak, played as an adult by James Ransone and as a youth by Jack Dylan Grazer.