TAB S7 fe. Had a problem with colour looking very faded. Tried to change to Vivid mode under display settings but made no difference. Spoke with online support who could not find a solution and now waiting for a further call back.
BUT meanwhile after searching found that if you go to settings, display and look at the options on the right then go right to the bottom of the options there is a blue written option:visibility enhancements
Click on this and then on the colour correction (this may already be set as ON as a default) Turn this to OFF. All the colours then returned to what they should look like.
If clicking on the little 'man' icon on bottom of screen (accessibility) this then takes you back to the duller colours.
Looks like you can go straight to these options by clicking on settings, go to accessibility and then click on visibility enhancements. Might be worth a try. Hope this helps.