How to reach the true final ending in Sonic Frontiers

Interestingly, Sonic Frontiers contains a true, secret ending that players can access through a rather simple method.

Sonamy Fanservice Zone — The True, TRUE ending

Sonic Frontiers - True Final Boss & Ending

Sonic Frontiers - THE END [OC] : r/SonicTheHedgehog

Endings - Sonic Frontiers Guide - IGN

Sonic Frontiers - All Bosses & Secret True Final Boss Fight + OST

Sonic Frontiers' has its weird, bad hooks in me

Looks like the Final Horizon content is an option you're presented

Sonic Frontiers' Final Horizon Launches Today With New Trailer and

Sonic Frontiers: The Final Horizon, OT

Sonic Frontiers Secret Ending [Explained]

Sonic Frontiers: How To Beat The Secret Final Boss