plotting – Changing the Style of different lines in PlotLabel

This ?

Plot[x^2, {x, -10, 10}, 
 PlotLabel -> 
  Row[{Style["The top line should be bold and blackn", Black, Bold, 
     15], Style[
     "The bottom line should be a smaller font, black, and normal", 
     Black], 12}], 
 TicksStyle -> {Directive["Label", 10, Black, Thick], 
   Directive["Label", 12, Black, Bold]}]