Yes in some cases they "re-skinned" actual F1 race cars from actual races and digitally overwrote the image with their fake team's livery.
Also, at many tracks they also ran their fake team's real cars during breaks in the action between practice sessions or qualifying, to get scenes with their cars and drivers on the actual tracks in real time.
And then a couple of times, they actually pulled up their fake team's real cars to the back of the grid at the start of an actual F1 race, to get some establishing shots and some footage of their cars taking off at the same time as the other real, actual F1 cars. In those cases their fake cars peeled off at some point during the first lap, so as not to interfere with the actual racecars running the real race.
If you noticed, the Apex team was almost always starting in the final two places on the grid. That's because they wanted them to be filmed on the grid in real life without interfering, but it also worked for the plot of the movie because, in fact, their cars were supposed to be quite crappy until their upgrades arrived late in the season, and they would have been qualifying poorly, anyway.
Anyway, completely agree they did some creative and innovative things with both sound and cameras, and they should be nominated for a lot of awards.