I don't know if you're talking about Lightroom Classic CC 7.3 or the latest update that was provided this morning. If you're talking about 7.3, the profiles have been moved to the Basic panel. They're right beneath the histogram. There are several different sections, and one of them is labeled, "Camera Matching Profiles". I just installed the 7.3.1 update that was new this morning, and things are still the same. Right now I'm working with some old Nikon D40 images from about nine years ago, and all the camera matching profiles are there as well as several different categories of new profiles.
In addition to Jim's feedback, triple-check that you are editing a raw and not a JPEG or TIFF. Many profiles only appear for raws.