The main issue is likely atmospheric haze affecting distant scenery, which lowers contrast and makes backgrounds look milky. Some of your shots may also be a bit overexposed, which adds to the washed-out look.

What to do when shooting:

• Learn to use exposure compensation and try reducing exposure slightly if highlights look too bright.
• Shoot RAW if possible; it gives much more room to recover contrast and color later.
• Expect distant landscapes to lose clarity in heat, haze, or humid conditions.
• Photos with closer subjects should look better because there’s less atmosphere between you and the subject.

For photos you already have:

• Yes, they can often be improved in Photoshop or Lightroom.
• Start by setting proper black and white points to restore overall contrast.
• Increase contrast carefully and adjust color if needed.
• For the best result, use selective/local adjustments or masks: treat the foreground separately from the hazy background, since one global adjustment often won’t fix both.

Lightroom is often easier than Photoshop for quick color/contrast correction across many similar images.