How Cordova support Network Security Config introduced by Android 7.0?

You can achieve this by adding the edit-config tag to the Android platform in your config.xml, this is supported by Cordova Android Plugin v7.0.

You will need to create the Network Security Config file that you would create for a native Android application using the examples from Google.

Next in the Cordova config.xml you can use the edit-config tag to add the networkSecurityConfig attribute to the Application tag. Then you just need to copy the Network Security Config file as a resource for your application to the res/xml directory.

Here is an example of how this might look in your applications config.xml

...
<platform name="android">
    <edit-config xmlns:android="http://schemas.android.com/apk/res/android" file="app/src/main/AndroidManifest.xml" mode="merge" target="/manifest/application">
        <application android:networkSecurityConfig="@xml/network_security_config" />
    </edit-config>
    <resource-file src="network_security_config.xml" target="app/src/main/res/xml/network_security_config.xml" />
</platform>
...

What James answered works but if you have an application where you can't specify a domain or wants to allow clear text traffic for all domains, we need to set android:usesCleartextTraffic="true" in platforms/android/app/src/main/AndroidManifest.xml in <application> tag.

Because, in Android P (version 9, API level 28), cleartext support is by default disabled. To achieve this, just add the following in your config.xml inside <platform name="android">:

<edit-config file="app/src/main/AndroidManifest.xml" mode="merge" target="/manifest/application">
    <application android:usesCleartextTraffic="true" />
</edit-config>