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.

Frontier Hopes (if Sonic is the ONLY playable character) : r

Sonic Frontiers: How to unlock the true final boss & ending

Sonic Frontiers - How to Unlock the The End True Final Boss Fight

Sonic Frontiers update adds playable Tails, Amy and Knuckles

Update 3 Final Boss In Base Game [Sonic Frontiers] [Mods]

Sonic Frontiers (Video Game) - TV Tropes

Sonic Frontiers Secret Ending [Explained]

Spoiler warning for the Sonic Superstars True Final Boss : r

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

Sonic Frontiers' Final Horizon Launches Today With New Trailer and