In order to press the way you want, Portugal would have had to employ a full pitch press which would basically be suicide with the combination of their slow defenders, Pogba's passing, and Mbappe's speed. Pressing from around the halfway line was the correct decision.
The reason why it seems like Portugal weren't applying much pressure was because of the buildup play of France. If Pogba, Tolisso, Griezmann, Benzema, Kante, and Varane are all involved in the buildup playing triangles around the few players who could press higher, then of course the sensible decision would be to stand off and save energy and pressure for the moments when the ball progressed up the pitch.
Contrast France's quality of buildup to that of our infamous game vs Southampton in 19/20 where it seemed like Pogba was playing by himself in midfield with Bruno high up and Matic at CB, and you can see the difference in the 2 setups. The more advanced our buildup play is, the less opponents will be inclined to waste energy pressing us high as they know it won't work. City is a great example of this.