He's alright for a flick on/keeping it alive but I'm not sure he's the best at attacking headers. Certainly doesn't show in goals scored, anyway. Recall his xG nonsense being up there with Calvert-Lewin's last season.
Think the example you give was a poor one though - Calvert-Lewin scores that with or without Tarkowski. He's certainly not instrumental.
As for "drags other players with him" - he's the centre half that 9/10 we aim for. Players will mark centre halfs at corners.
I'm not so sure Calvert-Lewin gets as much of a free header without
Tarkowski being there. The entire defence was watching, reacting to
Tarkowski all game. Like others have across the season.
He also screens, like an Nba center, well for others (Onana did the same without much fanfare).
Edit: you get a better idea of that here
I'm fairly sure Carragher has described him as the best in the league from attacking set pieces and he's been picked out across lots of pieces of analysis as a big part of our set peice success.
He probably should score more, but just having him there is problematic for other teams. He's a menace to defend against.