All cars made after August 2013 and before the 2016 refresh include Xenon HID headlights. Prior to August 2013, Halogen was standard and the HID headlights only came with the Tech package.
There is no official retrofit from Tesla, but it is possible to buy new headlight assemblies with the related HID electronics and have Tesla replace them. One person did this for $2800 (including labor).
Some third parties offer general-purpose cheap HID retrofits, but we’d be concerned that the beam coverage may be different (in a bad way).