Totally agree, we haven't really had capitalism for most of my life. It is possible though, and most of US history included at least mostly free markets.
I was a software consultant for many years. I'd put that on the list of truly competitive marketplaces. People were either willing to pay me to do a job or they weren't, and I would have to adjust my prices and terms to try to increase or decrease my workload.
That’s one, and I suppose marketing firms to some extent also fit.
But these are small niches that don’t make a whole sector, and arguably it’s on the fringes comparatively to everything else
Broadly speaking the so called free market is only in its name