The election is called on election night, Democrats build a huge majority in the House and outright win the Senate. There would probably be less emphasis on the GA runoffs. The GOP leadership completely abandons Trump. I don't think the average voter would perceive things all that differently though.
Under a 16 point swing:
Cunningham, Gideon, Greenfield, Bullock, Gross, Bollier, Harrison, Espy, Hegar, and Ossoff all win outright, and Warnock would be a shoe-in.
Dems hold at least 270 seats in House.
Dems take hundreds of state leg seats, probably win control of TX House, FL Senate, MI House, PA House, NH House and Senate, MN Senate, IA Senate, NC House and Senate...