If Norris finishes third or higher in the Abu Dhabi GP he will become world champion, while fourth will be good enough as long as Verstappen does not win the race.
If Verstappen scores 12 more points than Norris in Abu Dhabi, they will be level on points and race wins, but Norris would finish ahead of the Dutchman due to having more second-place finishes this season.
Norris also has more second-place finishes than Piastri, meaning he would also be above his McLaren teammate in the standings on countback if they finish level on points.