If the symbol can be found in Names, two links are created: one each for local and online documentation. For some System names, a link may not always be present but it is rare. If the symbol is not readily found, a search page is opened up at the Wolfram site.

s = "Part"
If[MemberQ[Names["System`*"], s]
 , RowBox[{Hyperlink[Button["Local"], "paclet:ref/" <> s]
    , Hyperlink[Button["Online"], 
     "https://reference.wolfram.com/language/ref/" <> s <> ".html"]
    }] // DisplayForm
 , Hyperlink[Button["Search"], 
  "https://search.wolfram.com/?q=" <> s <> "&skip="]
 ]

You can experiment with this and turn it into a function as you see fit.

If the symbol can be found in Names, two links are created: one each for local and online documentation. For some System names, a link may not always be present but it is rare. If the symbol is not readily found, a search button is generated for the input string that leads to a search page at the Wolfram site.

s = "Part"
If[MemberQ[Names["System`*"], s]
 , RowBox[{Hyperlink[Button["Local"], "paclet:ref/" <> s]
    , Hyperlink[Button["Online"], 
     "https://reference.wolfram.com/language/ref/" <> s <> ".html"]
    }] // DisplayForm
 , Hyperlink[Button["Search"], 
  "https://search.wolfram.com/?q=" <> s <> "&skip="]
 ]

You can experiment with this and turn it into a function as you see fit.