Apple - Why quarter step increment on brightness, volume and backlight is not working on a Touch Bar MacBook Pro?
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.
Quarter-step adjustments are still alive and well.
I'm running a 2019 MBP and all you have to do is expand the control strip and hold Shift and Option while toggling the desired Up or Down buttons.
Control strip minimised:
Control strip expanded:
Keep in mind that the control strip can be customised, so what I have on mine may be different to yours, but the volume and brightness up and down buttons are still available as options.
I have recorded a YouTube video to demonstrate.
I am on 13-inch, 2019 MacBookPro with Mojave and touch bar.
The quarter increments option ⌥ + Shift ⇧ + either of:[volume , brightness , keyboard backlight], works just fine (same as on my mid 2014 13" MacBookPro did).
One note though: the increments by 1/4 work all the way down to 0 with the sound, for the keyboard it's really hard to tell the difference of 1/4 vs 1, but for screen it only works in 1/4 increment from full to 1 bar; There is no difference between 1, 3/4, 1/2, 1/4 bar which is a real shame because that is where it would be the most useful for me. :'(