SetOptions[EvaluationNotebook[],
 StyleDefinitions -> Notebook[{
    Cell[StyleData[StyleDefinitions -> "Default.nb"]],
    Cell[StyleData["Graphics", All], FontFamily -> "Times"]
    },
   StyleDefinitions -> "PrivateStylesheetFormatting.nb"]
 ]

SetOptions[$FrontEndSession, PrintingStyleEnvironment -> "Working"]

plot1 = DensityPlot[x, {x, -1, 1}, {y, -1, 1}, PlotLabel -> "Plot 1"]
plot2 = DensityPlot[x, {x, -1, 1}, {y, -1, 1}, PlotLabel -> "Plot 2", PlotLegends -> Automatic]