If you loved SPY x FAMILY CODE: White, try Fighting Spirit: Champion Road
A bridge between a film you've already seen and one most people haven't. Fighting Spirit: Champion Road has roughly 9.0× fewer votes than SPY x FAMILY CODE: White — it's a deeper cut, not a mainstream recommendation. Here's what they share, and what the second one does that the first one doesn't.
What they share
Theyboth carry the playful mood tag, and they sit in Action / Animation / Comedy territory. If that's the register that drew you to SPY x FAMILY CODE: White, the second film will land in a comparable space — through a different lens.
What Fighting Spirit: Champion Road is
Here's a boxing anime that really wants you to root for its underdog. Featherweight champ Ippo must defend his title against a med student also after his girl. The presence of old rivals adds some spice, but mostly this just wants to get you pumped.

