We just bought a 2019 Golf ES last week and like you, I started looking at speaker option upgrades and can't seem to find out much at all, surprisingly.
Crutchfield helped me out a bit and evidently the front doors have 6-1/2" midrange/woofers and the rear doors have 5-1/4" drivers, while the component tweeters are mounted in the A-pillars. I have a '15 Cherokee Trailhawk and swapped all six speakers in three hours and they are a serious improvement, but from what I've found so far, the Golf isn't nearly as simple.
I need to research this more and get it figured out.
Crutchfield helped me out a bit and evidently the front doors have 6-1/2" midrange/woofers and the rear doors have 5-1/4" drivers, while the component tweeters are mounted in the A-pillars. I have a '15 Cherokee Trailhawk and swapped all six speakers in three hours and they are a serious improvement, but from what I've found so far, the Golf isn't nearly as simple.
I need to research this more and get it figured out.