Button["set",
  FrontEnd`SelectionSetStyle[FontColor, RGBColor[{1, 0, 0}]];
  Print[CurrentValue["SelectionData"]]]

Button["set",
 SetOptions[NotebookSelection[InputNotebook[]], FontColor -> RGBColor[{0, .7, .5}]];
 Print[CurrentValue["SelectionData"]]]

(
 SelectionMove[#, All, Cell];
 MathLink`CallFrontEnd[FrontEnd`SelectionSetStyle[#, "Title"]]
   ) & /@ Cells[CellStyle -> "Input"]