This one demonstrate both CheckBox tool and how to change Font Style at runtime.

Update button - on click event

                procedure TForm1.Button1Click(Sender: TObject);
                begin
                      { Clear previous font style, this step is not necessary }
                      Panel1.Font.Style:=[];

                      { Check for Bold option }
                      if CheckBox1.Checked Then
                           Panel1.Font.Style:=Panel1.Font.Style+[fsBold]
                      Else
                           Panel1.Font.Style:=Panel1.Font.Style-[fsBold];
                      { Check for Italic option }  

                      if CheckBox2.Checked Then
                           Panel1.Font.Style:=Panel1.Font.Style+[fsItalic]
                       Else
                           Panel1.Font.Style:=Panel1.Font.Style-[fsItalic];
                       { Check fro underline option } 

                       if CheckBox3.Checked Then
                           Panel1.Font.Style:=Panel1.Font.Style+[fsUnderline]
                       Else
                           Panel1.Font.Style:=Panel1.Font.Style-[fsUnderline];
                end;

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