Fan Casting "Long Live the King" in Godzilla vs. Shin Godzilla

In the first post-credit scene, Ren Serizawa; who was last seen in Godzilla vs. Kong, is having a conversation with a unknown person at an abandoned Monarch outpost in the Pacific Ocean. The unknown person turns out to be Alan Jonah. They talk about what their plan is to kill Godzilla. Ren pulls a lever, opening a hatch. Something slowly comes out of the hatch, revealing a new mecha. Alan says his line from KOTM, "Long live the king". The mecha is slowly revealed, from bottom-to-top, until we get a good look...at a mechanized version of King Ghidorah. It roars, then we cut to black.