You might be wondering why I focus so much on whether teams dominate passing when the score is tied (or within one goal.) This data from the English Premier League shows the percentage of total complete passes made by the home score depending on the score:

You'll notice numerous distinct patterns here:

1) The home team is much more likely to have the lead (94%, actually)

2) The home team controls passing when the game is tied; when they're up one, the visitors control it; when they're down one, they control it even more than when the game is tied.

3) At +2 or -2 goals, there's no pattern - this is because a two-goal margin is almost insurmountable. They occur primary when one team is vastly better than the other, meaning that there's no need to play defensively with the lead. And when they occur, teams are often not playing with their best players, which impacts the game much more than the strategy they're employing.

We don't have home teams per se in the World Cup, but we can look at passing data for 1- and 2-goal leads thus far:

We see similar effects here - when teams are up 1, they control a lower percentage of total passing. But when they're up 2, it probably means they're facing an inferior opponent, and so they dominate rather than playing defense.