De Bruyne has made 9 assists in 11 apps in EPL so far this season - the most in the campaign. Sancho has made 6 assists in Bundesliga in 9 games, which makes him the assist king in the league(Thorgan Hazard and Muller have both made 6 assists but they have made more apps than Sancho).
Check the list of assists kings of the top 5 leagues:
De Bruyne(EPL) - 9 in 11 games
Rodrigo(La Liga) - 6 in 11 games
Sancho(Bundesliga) - 6 in 9 games
Luis Alberto(Serie A) - 9 in 12 games
Slimani(Ligue 1) - 8 in 9 games