When a person becomes a former president

and I hope he suffers greatly(bigly) to quote a person whose ignorance has shown every day because of his malignant narcissism.

that Trump might make a play for his own media empire. His Twitter account is one outlet for him to keep mucking about, but that won't be near enough for him. He'll want to be in front of the cameras frequently and portrayed only as a hero. His own network would enable that.

by the taxpayers he tried so hard to screw. Of course if he goes to prison, he'll have security
and health care too. If he tries to run away, he'll lose that.
At this point, I think his safest landing place will be in prison. 90% of the world would like to
read his obituary.

Without the media coverage

Without the media coverage

detail to the former presidential detail, the White House Communications Agency uninstalls all of the communications equipment from Mar-A-Lago, the military aides sign off and head to the airport, etc.

He's going to go from a Secret Service detail of dozens providing the tightest, highest level of protection on earth to few very new rookie agents or almost-ready to retire agents, no metal detectors, no more limousines and motorcades, just one SUV and maybe a chase vehicle. no special White House phone lines with a military communications expert always on the other end ready to patch him through to whomever he wants anywhere in the world, just regular hardlines with dial tones and cell phones with no special features and maybe a signal, maybe not.

It's going to be such a comedown. Sweet.

However, trump* has never known a quiet life and has spent his entire existence doing his UTMOST to remain in the spotlight. His ego demands constant adoration and he know the adoration from his family is probably financially inspired. Getting that from complete strangers who cling to his every word and never question or doubt him is unlike any drug he can score with a prescription or convenient supplier.

If the media ignores him, after January 20, his antics will become epic.

What will happen when he holds rally's and claims he is the "true president"?

I'm hoping that once he's out of office, his rants will either land him in jail for insurrection or in the mental hospital for grandiose delusions.

His narcissistic self will miss the pomp and perks and loyalty that came with the office.
His businessman self will continue to attempt a hostile takeover, as if the country was a corporation. I hope he feels the loss of prestige "bigly".

...to not have to be 100% all the time. Of course I'm paraphrasing, but it seems a normal person wouldn't necessarily miss that. Now, as the OP mentioned, this is basically the worst case scenario for a narcissist like Trump.

that air traffic over Mar a Lego is suspended when he's there. That will end Jan 20. It's on a flight path and all those big, noisy jets will again disturb Oranges tranquillity every few minutes. Love it!