Hi ankit9989,
Since different models will have different display properties, we'd recommend comparing the display with another device of the same model to confirm whether what you're seeing is expected . If needed, find an Apple Store near you here: Find Locations
You mentioned already having True Tone and Night Shift off. Let's also ensure there aren't any Accessibility features that can impact the the display's color. Specifically, Invert Colors and/or Color Filters. Use display and text size preferences on your iPhone, iPad, and iPod touch covers where you can find each setting.
"To use Invert Colors, open the Settings app, then tap Accessibility > Display & Text Size. Turn on Smart Invert or Classic Invert."
"Open the Settings app, then tap Accessibility > Display & Text Size > Color Filters. You'll see three examples of color spaces to help you select an option that fits your needs. Swipe left or right on the examples to find a filter that works best for you."
Lastly, About the Super Retina display and Super Retina XDR display on your iPhone has some information about the hue of your display changing when you look at it off-angle.
If you look at an OLED display off-angle, you might notice slight shifts in color and hue. At reduced display brightness levels against black backgrounds, you might notice a slight blur or color change while scrolling. These are characteristics of OLED and are normal behavior.
Cheers!