If you plan to post process the photos on a PC, then the default zero values are probably the best choice for you.
If you’re using the photos directly from the phone for sharing or printing, then you might want to adjust these according to your personal taste.
The optimum level of sharpening is typically different for print and for display screen. For printing, consider adding some sharpness. However, the best settings depend on the print or display size, and personal taste as well.
If you’re feeling a bit adventurous, adjust the sharpness to slightly negative. You can also produce creative shots by using extreme values for some, or all, of these three settings, especially if you combine the settings with a colour tone setting, such as sepia or black and white. Note however, that you can’t convert a sepia or black and white photo to a normal colour photo afterwards.
Also, remember that the colours look more saturated when you view the photos on a large screen, compared to viewing them on the phone screen.
To change these settings, in camera, select the settings icon, and in the Creative shooting mode settings, scroll down to Saturation, Contrast, or Sharpness.