Touching up walls without painting the entire surface is tricky and success depends on whether you have the original paint and follow these steps.
How to do Paint Touch Ups and Small Wall Repairs - Home Painter
Can I fix a few oil stains (2.5 cm long x 0.5 cm wide) on my wall
Is it worth taking taping and texturing a mobile home wall? - Quora
Touch Up Painting Job or Repaint
How to Touch Up Paint The Right Way
Can I fix a few oil stains (2.5 cm long x 0.5 cm wide) on my wall
Can't match touch up paint to original coat
Help with touch up : r/paint
Is there a way to even out the paint without painting whole wall - Home Improvement Stack Exchange
The Best 7 Steps For How To Touch Up Wall Paint With Painting Tips
Blogs
3 Ways to Touch up Paint
How to Paint a Room: 10 Steps to Painting Walls Like a DIY Pro
Why are my touch ups drying darker? The paint is a few years old, diluting with water isn't helping : r/paint