Specific to XCode 9.1:
You can refere to @Krunal's answer above or follow below steps
its bit tricky to adjust Simulator size.
If you want to zoom your simulator screen follow below steps :
Goto Window->Uncheck Show Device Bezels
Goto Window->select zoom
after doing this you can resize your simulator by dragging edges of simulator.
Pixel Accurate : Its to display your simulator in same size as Physical device pixels, if your screen size doesn't have enough resolution to cover dimension it would not enable Pixel Accurate
option.
Alternate is change simulator to landscape mode by clicking ? + ? ,then you could click ? + 2 to select Pixel Accurate option (make sure you have disable Show Device Bezels
to reduce size.