Perhaps an odd topic when your WP dashboard has an upgrade button and if you are hosting with a major ISP then this option should work.
For self hosters [XAMPP, WAMP etc.] you almost certainly have to do this manually.
Before we start, always a good idea to do a complete backup, so just zip up your current WP folder and keep it safe. Also a good idea to copy the MySQL WP database to another temporary database with your phpMyAdmin or whatever you use for MySQL management.
Download the latest version from WordPress and unzip it
Delete the file wp-config.php from this unzipped folder
We are in essence replacing some folders and some files from the live WP folder structure with the new WP folder structure you’ve just created with the above unzip.
If it helps open up two windows side by side with the LIVE Master folder on the LEFT and the new downloaded folder on the RIGHT as below.
Optionally disable any plugins you have running on your WordPress site.
Delete the LIVE [Left Hand Side] wp-admin and wp-includes folders and copy across the NEW [Right Hand Side] versions
With the exception of wp-config.php, which you should have deleted from the RHS version, replace or copy across all the root or top level files from the NEW [Right Hand Side] to the LIVE [Left Hand Side]
On each Window move into the wp-content folder. They will look the same and copy across the Index.php file from the NEW [Right Hand Side] to the LIVE [Left Hand Side]
Restart or refresh your wp-admin panel and you will be prompted to upgrade your WordPress Database
Optionally restart any plugins you may have disabled