Thank you for sharing the screenshot.
Is this screenshot taken from Acrobat's New UI? With the new user interface, the "Open document in new tab" option has been disabled.
Try changing back to the old UI from View > Enable|Disable New Acrobat (Mac) or Hamburger menu > Enable|Disable New Acrobat (Windows). For more details, click here
and see if you get the option back in preferences.
If this is not the case, let us know the exact version of Acrobat. Open Acrobat>help>About Acrobat.