help trying to make something more 'readable'

[rich2005]

If you want to go a bit further. All in one screenshot for reference https://i.imgur.com/p39lxWH.jpg

1. The image is in indexed mode so change to RGB Image -> Mode -> RGB
2. Use Filters -> Generic -> Erode to grow the darker areas.

That might be enough or
Repeat Erode
3. Apply a small (default) Gaussian blur Filters -> Blur -> Gaussian blur
4. Apply a default or small adjusted Threshold Colors -> Threshold