Vertical tabs are really convenient, add an setting for Brave browser

[Fingolfin]

You can enable the beta vertical tabs with a flag.
More discussion on this in this post:

Side / Vertical Tabs

It is important to remember that ‘Vertical Tabs’ is still an experimental feature and isn’t very old. I would suspect that customization is something that can be expected in the future, however, functionality is usually the primary goal of experimental features. Cosmetic appeal is definitely something that would be more along the lines of features that are stable and ready for production. You should be able to customize the tabs now through chromium CSS edits, but that is definitely going to r…