As an A7 III user, you're used to RAW files that are 27 - 48 MB in size each, so the 13 PM's 27 MB is right in the same ballpark; there's a reason 13 PM HEIC files are only about 5 MB in size.
When I bring a RAW DNG file into my Mac I don't see any of the "supercharged" colors you reference; in fact only color temperature is set, all my color sliders are at zero.
For example, this is what I see in Photoshop Elements 2021's Camera Raw 13.0 when I open a quick photo I shot with my 13 PM:
Apps are for people who want "one click" solutions, no matter what Adobe says, whether it's Apple's Camera app or Lightroom Mobile.
If you want the best results you will have to grade and adjust every single photo you take; the same is true for anything from my Nikon D850. I would never dream of posting a JPEG directly processed by the camera; that's kind of the whole point of RAW.
For example, I regularly take photos that I upload to Facebook from my D850; it usually takes me a minimum of two to three minutes to examine, grade and process each one; why would I expect any less of DNG files from my 13 PM?
On the other hand, what comes straight out of Camera is good enough in most cases for just casual shots.
Feel free to complain to Apple here as most people love the defaults and Apple is trying to please them; the fact that we got RAW mode at all means Apple wants to keep photo pros happy, too but not at the cost of disappointing average users.
Feedback - Camera - Apple