The following syntax works:
CellPrint[Cell[
BoxData[ToBoxes[Plot[Sin[x], {x, -2, 2}]]],
"Output",
CellTags -> {"target"}]
]]
It is documented under Cell -> Scope.
Hyperlink["link", {EvaluationNotebook[], "target"}]
(* Out: hyperlink pointing to the plot *)
MichaelE2 points out in a comment that ExpressionCell
can be used:
CellPrint@ExpressionCell[
Plot[Sin[x], {x, -2, 2}], "Output", CellTags -> "tag"
]
Note that you can also add tags manually through the drop down menu that you get by right-clicking on cells: