What would it be like if Olympus Mons was on earth, starting at sea level?

Olympus Mons is the tallest and biggest mountain in the Solar System. It is approx 21.9 km tall and 600km wide at its base. Mauna Kea, also a shield volcano, is our tallest mountain from the base and is less than half the height at 10.2 km, while Everest is only 8.8 km above sea level. If Mauna Kea started at sea level it would easily be the tallest mountain in the world, but still a comprehensible scale next to the Himalaya and Karakoram ranges. But a mountain the size of Olympus Mons on Earth would surely be a whole different ballgame.

A few plausible assumptions:

- the summit would pierce the mesosphere, making it ridiculously cold and possibly host to a higher-than-average frequency of meteor strikes

- no conventional winged aircraft could crest its summit (only certain specialized military or research vehicles)

- no rotor aircraft could get anywhere even remotely close to the summit due to the mountain’s height + width

- over half of its total elevation would lie within the Death Zone, where humans can’t survive without supplemental O2

- it would probably be thickly glaciated on all sides since it’s so “flat” as a shield volcano

- it could cover the entirety of France

But with those out of the way, what else? Atmospheric and optical effects? Weather / climate etc? Geology traits and factors? Etc..

Extra credit: how would we put someone on top? Best I can think of is, either a daring summit touchdown with a high-altitude helium balloon (if takeoff/landing is even possible at such altitude) or a very long mountaineering expedition with the scale and logistics of nearly moon landing proportions, as it would require a summit team to survive weeks if not months in the death zone while covering hundreds of miles of glacial terrain.