Parsons had one of the all-time great rookie seasons, so there is a significant chance he regresses, even if slightly.
Now does that mean he goes from:
84 tackles, 20 TFLs, 13 sacks, 47 pressures, 3 FF, 3 PDs
to
86 tackles, 15 TFLs, 9 sacks, 49 pressures, 2 FF, 1 PD, 1 Int
or
40 tackles, 2 TFLs, 2 sacks, 10 pressures, 0 FF, 2 PDs
Now, I would not bet on stat line 3 unless he is dealing with injuries and then goes on the IR early in the season.
Then even if he "only" hits stat line 2, which would be a regression, that is STILL a great season. And with teams game planning for him in Game 1 knowing what he is capable of at the NFL level instead of trying to guess with little film on him, his production could very well "regress" this much.
But I also think it is just as likely that he will improve in most stats across the board.
The one stat I would expect to not jump up much higher or much lower is sacks. Teams will be VERY prepared to stop Parsons as a "traditional passrusher", so I believe that DQ lines up Parsons as a DE too much, it will hurt Parsons passrushing production. But if DQ can find a way to get Parsons one-on-one against offensive linemen by moving him around and rushing him from different spots, his passrushing production could improve.
In any case, I expect Parsons to have another Great Season in 2022.
JMHO