These are taken on film. So you're converting the negative into a positive when scanning them. During that process you're always working to adjust the colours to your liking. It's not like digital where there's a standard camera profile. Film photos leave room to imagine. That said, Portra has a lot of blue in it, so I simply brought out the blue tones in the sky and added some warmth. Used a bit of VSCO in post in Lightroom, too.