You can style a polygon based on two levels, one is at the global level, and the other is at the Individual level.
** Individual styles will overrule the Global settings.
It is better to use global styles if you want the same look throughout all the polygons on the map. Global styles save time and eliminate the need for each shape to be styled separately; update settings at one location, and it will automatically apply to other polygons.
To give a single style across all polygons in a map, click on the Style -> Polygon.
There are multiple options to change the fill and stroke color, opacity for both normal and hover states.
To apply styling on an individual polygon, create a polygon, click on the corresponding Style option, and adjust the fill and stroke settings.