Diagnosis
The monitor likely shipped with a very conservative default color profile. The out-of-box settings are often set for sRGB color space with low brightness and contrast to meet energy standards, which can look flat.
How to Fix It
Let's wake those colors up. Use the joystick to open the OSD. 1) Go to Picture. First, set the Picture Mode to 'User'. This gives you full control. 2) Adjust Brightness and Contrast to your liking (start around 70-80 for each). 3) Now go to Color. Here, set Color Temperature to 'Warm' or 'User' (User lets you tweak Red/Green/Blue gains—start with 50-50-50). 4) Crucially, find the Gamma setting and try 'Gamma 2.2'. This is the standard for PC content and will add depth. 5) Finally, go to the Gaming menu and make sure Adaptive Contrast or VRB (Visual Response Boost) is Off, as these can crush colors.
If That Didn't Work
The issue might be on your PC's end. Right-click your desktop, go to your graphics control panel (Nvidia Control Panel or AMD Radeon Software). Under 'Display' > 'Change resolution', make sure the output color depth is set to the highest available (like 8-bit or 10-bit) and the output dynamic range is set to 'Full' instead of 'Limited'. Limited range will cause a washed-out look.
Heads Up
If you're coming from a highly saturated VA panel or a TN panel with crazy vibrancy, an IPS panel like this one aims for accuracy, not oversaturation. It might take a day or two for your eyes to adjust to more natural colors.