How to override in magento 2 adminhtml template view files?

You need to create an admin theme and assign for the admin area

so first, we will create new admin theme.

Step1: Create a theme directory in the app/design/adminhtml/[Theme-Namespace]/[themename] and create theme.xml file. Put below code in theme.xml

<theme xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Config/etc/theme.xsd">
    <title>Admin Custom Theme for Magento 2</title> <!-- your Custom theme's name -->
    <parent>Magento/backend</parent> <!-- it must be parent theme. Example: Magento/backend -->
</theme>

Step2: Create registration.php in appdesignadminhtml[Theme-Namespace][themename] and add following code

<?php
    use MagentoFrameworkComponentComponentRegistrar;
    ComponentRegistrar::register(ComponentRegistrar::THEME, 'adminhtml/[Theme-Namespace]/[themename]', __DIR__); 
?>

Step3: Create folder Magento_Catalog in appdesignadminhtml[Theme-Namespace][themename]Magento_Catalog and

Step4: Create folder template in appdesignadminhtml[Theme-Namespace][themename]Magento_Catalogtemplates and
add this your file catalog.phtml

Now we need to assign new theme to admin area

Step1: Create a new module and create di.xml file app/code/Vendor/Module-Name/etc/di.xml

<?xml version="1.0"?>
    <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
        <type name="MagentoThemeModelViewDesign">
            <arguments>
                <argument name="themes" xsi:type="array">
                    <item name="adminhtml" xsi:type="string">[Theme-Namespace]/[themename]</item>
                </argument>
            </arguments>
        </type>
    </config>

Step2: Create module.xml

<?xml version="1.0"?>
    <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/Module/etc/module.xsd">
        <module name="Vendor _ Module-Name" setup_version="1.0.0"/>
    </config>

Step3: Create registration.php file

<?php
        MagentoFrameworkComponentComponentRegistrar::register(
            MagentoFrameworkComponentComponentRegistrar::MODULE,
            'Vendor _ Module-Name',
            __DIR__
        );

Now run all command and check you changes.