I recently got a Lenovo ThinkPad T495 where I dualboot Ubuntu 18.04.
Unfortunately I cant adjust the screen brightness.
I have already tried with this solution (Brightness problem Ubuntu 18.04 LTS), but with no luck.
acpi_backlight=video option seems to be closer to solution for me, in the sense that at least the brightness bar goes up and down properly when applying this fix (only the bar changes not the actual brightness!). But I guess my configuration file should look a bit different from the one provided in the link.
When I run
sudo lshw -c video | grep 'configuration'
to find out my graphic drivers I only get this answer: