Previously on my MacBook Air 2013 I was able to increment/decrement screen brightness, volume and the keyboard backlight in quarter steps when pressing ⌥+⇧ and a media key. This doesn't seem to work anymore with the Touch Bar on my 2019 MacBook Pro 16" running macOS Catalina.
It seems to work for some people as can be seen from https://youtu.be/_MQFS-0eqtk and https://youtu.be/dTCbKYIqLqs, but it does not work for me. I've tried on a 2019 15" on Mojave and on my personal 16" and work 16" on Catalina.
Okey, I have tried two of my colleagues 16" MacBook Pros and the feature works fine for them. This must be something just wrong with my system.
Best Answer
Tap the arrow on the left of the system area to expand the full list of system buttons, then use the brightness increase and decrease buttons from there.
(If you've removed them, you might need to go to View → Customize Touch Bar and add them back in.)
Since those buttons have the exact same function as non-Touch Bar models, you can use the alt + shift combination to get the quarter-step changes.