Heard this story numerous times. And it never turns out to be true. Had a guy show up at chess club some years ago bragging how he is rating 2500+ online. He lost to a 1300 at a classical time control and we never seem him again.
Especially when someone creates their account and selects 1800 as their first rating.
There is a kid in his 20s that came to the local club ~3 months ago. He decided he wanted to play OTB. He was talking with the TD and showed him his chess.com ratings. 2450 in blitz, 2375 in rapid, 2300 in bullet. Starts his first rated game in the lower section against a 900-rated 11-year-old. The game was over in 22 moves with the 11-year-old having a crushing position from move 6.
It is always the same: someone with a fairly new account comes on claiming they have violated the rules of nature and achieved great results. Until you look deeper and see they are only really good at data entry.
You get 2100 highest rapid rating first. Or at least stay around 2000 rapid and 1800 blitz.
Tell me you do not know what you are talking about without telling me you do not know what you are talking about.