Display Screen or Portion Thereof with a Graphical User Interface or Set of Graphical User Interface Elements

FIG. 1 is a front view of a display screen or portion thereof with a graphical user interface according to a first embodiment of the new design; and, FIG. 2 is a front view of a display screen or portion thereof with a set of graphical user interface elements according to a second embodiment of the new design. The outermost rectangular broken lines in the figures illustrate a display screen or portions thereof and form no part of the claimed design. The remaining broken lines illustrate elements of the graphical user interface or set of graphical user interface elements that form no part of the claimed design. The bracket shown in FIG. 2 indicates a set, and forms no part of the claimed design. The graphical user interface elements of the set are arranged relatively on the drawing sheet for the convenience of illustration, and the placement of each graphical user interface element relative to another, or to the drawing sheet, forms no part of the claimed design.