Do pilots ever intentionally takeoff or land downwind?
It's perfectly legal, but check the Chart Supplement (or AFD, or instrument approaches) to see if there are special exceptions for that airport.

If it is a non-towered airport and you aren't assigned a runway, you should of course try to use the prevailing runway that is already in use by other traffic in the pattern when it makes sense.

Some airports have obstructions in one direction of their runways that make it necessary (or safer) to always land or depart in a certain direction.

Some runways have a steep incline in one direction, making it preferable to land upslope and depart downslope.  (For example Lukla, Nepal: YouTube)

It's also common for larger airports to have preferred directions for arrival or departures in order to keep the flight volume high, even when the wind prefers other runways.

However, that usually relates to operating with intentional crosswinds at an airport that has parallel runways in a primary direction (allowing them to conduct more simultaneous flight operations), but not in the intersecting direction.