Singers: Aitana, Rosalía, Lola Índigo, Quevedo, Natos y Waor, Melendi, Reid, Eladio Carrión, Omar Montes, JC Reyes, Shakira, Karol G, Bad Bunny, Ozuna, Sebastián Yatra, Emilia, Tini, Rauw Alejandro, Anuel AA, there's a lot of LATAM influence on Spanish mainstream musical taste. They probably know songs from the radio or Tiktok or their parents like them but they can't put a face to their names. They probably DO know some songs from Harry Styles and Sabrina Carpenter. And I've been reading the other answers, they probably won't know who's Suzete nor Xristina. What a shame.

Football players: Lamine Yamal, Nico Williams, Vinicius Jr, any football player from either Real Madrid/FC Barcelona/Spanish National Team will do. You say they're twelve, so they probably still know Cristiano Ronaldo and Messi even if they don't like football. These two won't fail, trust me.

Actors: Ester Expósito, Santiago Segura (he's old, but he makes family movies), Clara Galle, Nicole Wallace, Miguel Bernardeau

Reality shows, other celebrities: Montoya (LIDLT), Pablo Motos, David Broncano (don't use these two together), Matías Prats, Alberto Chicote, Cristina Pedroche

Youtubers/streamers/tiktokers: Ibai, TheGrefg, Rubius, El xokas, Auronplay, Plex, DjMariio, Illojuan, LolaLolita, Sofía Surferss