If they record on location then they usually use directional mics that only capture the person speaking the lines. That’s why you see those mics on a stick being held directly above the actors sometimes.
Everything else is added in the edit bay. Even the lines are sometimes re-recorded in the studio, that’s called ADR.
For background sounds/noise they sometimes just record empty rooms and spaces so they have that steady ambiental sound of the space itself, and then they layer sound effects and dialogue on top of that.
Of course there’s been pre-existing libraries of those kinds of sounds for decades so you don’t have to record them for every film.
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