Can't seem to find a Menu Bar Dictionary

I keep the Dictionary application that ships with macOS in the Dock about mid-screen for the least amount of mouse movement to click on it. You can also use a trackpad three-finger tap (must be configured in trackpad preference), or simply hover the pointer over a word you want to look up and press control+command+d to perform the lookup in place.

You can even use the Safari browser to open the Apple dictionary application to a chosen word by entering the following in the address field:

dict://word

Safari will open a panel requesting permission to allow it to open the Dictionary application. Click Allow. and then the definition of word would be shown.

Did you look in the App Store under "dictionary"?