If you have an active subscription (or a Maintenance & Support plan for a Classic licence), you can download any updates as soon as they are released.
SketchUp will even notify you if a new version has released. A notification message will pop up when you are using an outdated version of SketchUp.
If you get the pop up message, you can simply follow the notification links and download the latest version. Or, you can click on the Download All link to download it directly.
If you are changing from a major version (eg. 2019 to 2020), then you will want to remove the older version from your task bar (if you had added it there), and then add the newest version.
Some people completely remove old versions of SketchUp from their computer. Others like to leave the version below current - just in case the newest version does not support one of your favourite extensions.
Note: Extensions often take several weeks after a major update before they become compatible.