If we follow the laid out timelines as stated by Mike Pompeo and Donald Trump, we will have a rough four years but Republicans will take back the House and Senate next election.

If Joe (or Kamala) leave office for any reason and Trump is instated as president after January 20th, 2023 then he will serve less than 2 years of a term.

Per the 22nd Amendment, this means he can run for president again in 2024 and serve for another 4 years, or a grand total of approximately 10 years.