When you buy/lease a brand new car, are you able to add things/customize it at the dealer?

In 2014 my friend financed a base model Jetta brand new red. However his model came with fog lights and LED turn signals but had hub caps. However, my other friend had a 2014 Jetta as well and had the middle trim and had no fog lights or LED turn signals but had aluminum alloy rims.

Can you add things like that to a car? I know at Honda if I wanted Fog lights on the middle trim they would ask me to upgrade entirely to the highest trim which i don't need, I just want the fog lights

There are always optional extras you can add, for a price, but not everything, & nothing illegal of course.

A Donald Trump Supporter should know that you can do this

That will depend on the car and the brand - some brands (usually the lower end) will only sell accessories as a pack. The dealer definitely wants you to buy the pack. But on other (usually higher end) cars, you can specify each and every component.

Check out e.g. - you can e.g. Specify you want logo'ed stem caps withouth getting anything else.

A lot of trim and wheels can be installed by the dealer as accessories.

Lighting options may be trickier and some manufacturers would offer those options from the factory only.

EVERY option that is part of a package is available separately from the package.
The salesman will probably try to sell you the next higher trim level in any case, but there are EXTREMELY few options that REQUIRE more than the base trim level and NONE that require the highest trim level.

That said, you may save by getting a higher trim level with features you won't use vs individually purchasing the options you want.