Have no idea what @limbo47800 is saying but...
OP -- your question: the optimal settings will be determined by your TV.
Maximum brightness should be set to the maximum nits (a measure of TV brightness) that your TV can do. Using google, I was able to find the max for my LG TV and set it to that value.
Paper White is how bright you want the UI elements to be. Put it lower for a toned down look, higher for a more neon looking. I go with 200 for that neon-look. This setting is really your preference and as far as I can tell does not affect anything in the game other than the vibrancy of the UI.
Tone-Mapping Midpoint is the trickier of the settings to get right. I found my optimal setting through trial and error. If you are finding indoor areas like parking garages too dark, then lift the value here. If things are washed out, lower. I found it best to go to a darker area to calibrate and fiddle with this until it looked just right.
For reference, on my 4K LG I have my max brightness set to 650 and my Tone-Mapping Midpoint is set to 1.65.
I have a Samsung QLED 50" TV but unable to find anything helpful, are you able to help?
Thanks for your help though!
You'll need to provide the model of your TV as Samsung makes lots of TVs.... or Google "Samsung QLED <model name> maximum nits" and you'll likely get an answer pretty quickly yourself! After that, you need to experiment with the mid-tone mapping point so it looks right to you. I suggest starting it at 0.5 and raising it from there in increments until you find it looks perfect.