Consider example

   ContourPlot[{(x - 2)^2 + (y - 2)^2 == 
       12, (x + 2)^3 + (y + 2)^3 ==8}, {x, -4, 4}, {y, -4, 4}, 
     PlotLegends -> 
      Placed[{Style["Region 1", 20], Style["Region 2", 20]}, {0.7, 0.82}]]

The result is the picture on the left. Could you please tell me to change the colour of the legend text and set for each plot legend set its own coordinate, see the picture on the right?

Try this:

Show[{
  ContourPlot[{(x - 2)^2 + (y - 2)^2 == 12, (x + 2)^3 + (y + 2)^3 == 
     8}, {x, -4, 4}, {y, -4, 4}, ContourStyle -> {Blue, Orange}],
  Graphics[{Text[Style["Region 1", 20, Blue], Scaled[{0.8, 0.8}]],

    Text[Style["Region 2", 20, Orange], Scaled[{0.2, 0.2}]]
    }]
  }]

Done. Have fun!