Create system config in magento 2

Update menu.xml

Rsgitech\News\etc\adminhtml\menu.xml

Add system configuration link in menu

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Backend:etc/menu.xsd">
	<menu>
	  <add id="Rsgitech_News::rsgitech" title="RSGiTECH" translate="title" module="Rsgitech_News" sortOrder="90" dependsOnModule="Rsgitech_News" resource="Rsgitech_News::rsgitech"/>
	  <add id="Rsgitech_News::news" title="News" translate="title" module="Rsgitech_News" parent="Rsgitech_News::rsgitech" sortOrder="50" dependsOnModule="Rsgitech_News" resource="Rsgitech_News::news"/>
	  <add id="Rsgitech_News::news_allnews" title="All News" translate="title" module="Rsgitech_News" parent="Rsgitech_News::news" sortOrder="10" dependsOnModule="Rsgitech_News" action="news/allnews" resource="Rsgitech_News::news_allnews"/>
	  <add id="Rsgitech_News::settings" title="Settings" translate="title" module="Rsgitech_News" parent="Rsgitech_News::rsgitech" sortOrder="60" dependsOnModule="Rsgitech_News" resource="Rsgitech_News::settings"/>
	  <add id="Rsgitech_News::news_config" title="Configuration" translate="title" module="Rsgitech_News" parent="Rsgitech_News::settings" sortOrder="10" dependsOnModule="Rsgitech_News" action="adminhtml/system_config/edit/section/rsgitech_news" resource="Rsgitech_News::news_config"/>
	</menu>
</config>

Copy

Create file system.xml

Rsgitech\News\etc\adminhtml\system.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_file.xsd">
    <system>
        <tab id="rsgitech" translate="label" sortOrder="250">
            <label>Rsgitech</label>
        </tab>
        <section id="rsgitech_news" translate="label" sortOrder="130" showInDefault="1" showInWebsite="1" showInStore="1">
            <class>rsgitech-separator</class>
            <label>News</label>
            <tab>rsgitech</tab>
            <resource>Rsgitech_News::news_config</resource>
            <group id="general" translate="label" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="1">
                <label>General</label>
                <field id="enable" translate="label" type="select" sortOrder="1" showInDefault="1" showInWebsite="1" showInStore="1">
                    <label>Module Enable</label>
                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
                </field>
            </group>
			<group id="storefront" translate="label" sortOrder="11" showInDefault="1" showInWebsite="1" showInStore="1">
                <label>Storefront</label>
                <field id="news_link" translate="label" type="text" sortOrder="1" showInDefault="1" showInWebsite="1" showInStore="1">
                    <label>News Link</label>
                    <comment>This is news link</comment>
                </field>
                <field id="set_limit" translate="label" type="text" sortOrder="2" showInDefault="1" showInWebsite="1" showInStore="1">
                    <label>Set The Number of Limit</label>
                    <comment>Set the number of limit for showing latest news</comment>
                </field>
            </group>
        </section>
    </system>
</config>

Copy

Create file config.xml

Rsgitech\News\etc\config.xml

You can set default value in system configuration

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
    <default>
        <rsgitech_news>
            <general>
                <enable>1</enable>
            </general>
            <storefront>
                <news_link>Latest News</news_link>
                <set_limit>10</set_limit>
            </storefront>
        </rsgitech_news>
    </default>
</config>

Copy

Then run below commands

php bin/magento cache:flush

Copy