Updating your WordPress Theme to the latest version is highly recommended and is very simple. You’ll get latest features and you’ll also be up-to-date with any security patches.

Now, updating your theme in WordPress is made very simple for you. Just go to Dashboard > Updates and select your theme, then click the Update Themes button.

Example to update Marlin theme:

or You can also navigate from Appearance > Themes and click update now.

To take a manual update, please refer to this article.