Some browser extensions can be used on mobile devices, but the availability and functionality of extensions can vary depending on the browser and the operating system. For example, on Google Chrome for Android, extensions can be installed, but they may not work as expected because they were designed to run on a desktop browser. The same goes for Safari browser on iOS. However, some mobile browsers like Firefox for Android and iOS have built-in support for browser extensions, and you can install and use extensions just like on a desktop browser.
There are also mobile apps that can provide similar functionality to browser extensions, such as ad blockers, password managers, and language translators. These apps can be downloaded from the App Store or the Google Play Store, and they can be used in conjunction with or as an alternative to browser extensions.