Press the Refresh key + the Show windows key + the Volume up key (repeat if needed)
Use the keyboard shortcut: Ctrl + Alt + Shift + Refresh (repeat if needed)
Open Settings
Select Device
Select Displays
Change Orientation to Landscape or Portrait (or Rotate as available)
If available, use the display rotation option in the quick settings panel
Sign out and sign back in if rotation options don’t appear
Update ChromeOS: Settings → About ChromeOS → Check for updates