I’ve recently just bought a Volvo v40 R-design with 190 horsepower from 2014. Currently there is mounted halogen headlights, but is it possible to mount original led headlights unit to a car this “old”?
It's quite a common upgrade to request, across all makes and models.
Normally people suggest the cost and effort isn't worth it. It would make more sense to factor in buying a higher spec car with xenon/LED included. There is, as mentioned above, both hardware to buy and fit and reprogramming of software.