You certainly can. 🙂

In the right colour combo it will look rather nice!

For best results, use the material appropriate paints.

If you have a modest budget then paint them. Use a really great primer like Zinster for better results.

If you are feeling more flush and up for the work consider removing them, repair any damage and replace skirting boards too- it will look bigger and better

Agree with both E D and Jonathan's suggestions all dependent on budget and how much work you are willing to do. If budget is an issue I'd paint it a lighter colour and also consider painting the interior of your door a lighter colour as well.

Big mirrors will make the space lighter and look bigger.

Painting the cladding will certainly brighten it up. Make sure you sand and apply 2 coats of primer, then 2 coats of eggshell or Satinwood, depending on paint brand. I think a nice taupe shade would look lovely. This is Purbeck Stone by Farrow & Ball.

Much brighter. Well done!

Wow! looks so much brighter what a difference painting it lighter made.