QGIS Layer Style – Adding intensity/color if elements overlay

How do I add a layer styling in QGIS?

Right-click on a vector layer and select Styles ► in the list in order to: see the styles currently applied to the layer. If you defined many styles for the layer, you can switch from one to another and your layer rendering will automatically be updated on the map canvas.
 

How do you use rule based symbology in QGIS?

3.3.5. Follow Along: Rule-based Classification

1. Open the Layer Properties dialog for the landuse layer.
2. Switch to the Symbology tab.
3. Switch the classification style to Rule-based.
4. Click and drag to select all the rules.
5. Use the ^{Remove selected rules} button to remove all of the existing rules.

How do I color different attributes in QGIS?

Right-click the layer again and choose Properties. This time choose Categorized from the Style tab. Categorized means the features in the layer will be shown in different shades of a color based on unique values in an attribute field.