1). Republicans take control of house and senate in 2022 (by hook or by crook).
2). The house elects Trump as speaker of the house. Note that the speaker doesn’t have to be a Representative. The house majority can select anyone they want, but probably has to be >= 25yo and US citizen.
3). The house then impeaches both Biden and Harris and the senate convicts both, thus removing both from office. The speaker of the house (Trump) is third in line and becomes president.
4). Since Trump has served less than half a term in his second term as president, he is eligible to run for president in 2024.
[Optional 5). House and senate introduce bills to repeal 22nd amendment to eliminate two term limit for presidents.]