Brave Sync menu item does not appear on menu as depicted in the How do I set up Sync help article.
Click the menu icon in the upper right.
Open your eyes.
Notice the Brace Sync icon does not exist.
Brave sync icon exists where the help article tells you to find it. Brave Version( check About Brave):
Version 1.3.115 Chromium: 80.0.3987.87 (Official Build) (64-bit) Additional Information: