Is my iPhone X still under warranty?..... I have a cracked screen

Keeping in mind the cracked screens are not covered by warranty, check your device coverage here:--> Check Your Service and Support Coverage - Apple Support

Regards

Giulio

Warranty or no warranty, the price of the screen replacement is the same as the out of warranty price. However, if you have AppleCare, it would be cheaper.

Check pricing here:

https://support.apple.com/en-us/iphone/repair/service/screen-replacement