Example configuration profile to install the uBlock Origin Firefox extension and set domains that can install extensions

FirefoxExtensions.mobileconfig

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
    <dict>
        <key>PayloadContent</key>
        <array>
            <dict>
                <key>EnterprisePoliciesEnabled</key>
                <true/>
                <key>Extensions</key>
                <dict>
                    <key>Install</key>
                    <array>
                        <string>https://addons.mozilla.org/firefox/downloads/file/1166954/ublock_origin.xpi</string>
                    </array>
                    <key>Locked</key>
                    <array>
                        <string>uBlock0@raymondhill.net</string>
                    </array>
                </dict>
                <key>InstallAddonsPermission</key>
                <dict>
                    <key>Allow</key>
                    <array>
                        <string>https://addons.mozilla.org/</string>
                    </array>
                    <key>Default</key>
                    <true/>
                </dict>
                <key>PayloadEnabled</key>
                <true/>
                <key>PayloadIdentifier</key>
                <string>com.example.config.firefox.14fd66f9-965d-406b-bb89-d0389761c422</string>
                <key>PayloadType</key>
                <string>org.mozilla.firefox</string>
                <key>PayloadUUID</key>
                <string>14fd66f9-965d-406b-bb89-d0389761c422</string>
                <key>PayloadVersion</key>
                <integer>1</integer>
            </dict>
        </array>
        <key>PayloadDescription</key>
        <string>Manages Firefox extensions</string>
        <key>PayloadDisplayName</key>
        <string>Firefox</string>
        <key>PayloadIdentifier</key>
        <string>com.example.config.firefox</string>
        <key>PayloadOrganization</key>
        <string>Example Org</string>
        <key>PayloadRemovalDisallowed</key>
        <true/>
        <key>PayloadScope</key>
        <string>System</string>
        <key>PayloadType</key>
        <string>Configuration</string>
        <key>PayloadUUID</key>
        <string>b8b453ae-fe18-4302-ab3f-a8c524e84ea7</string>
        <key>PayloadVersion</key>
        <integer>1</integer>
    </dict>
</plist>