TYPO3 v8 has reached its end-of-life March 31st, 2020 and is not maintained by the community anymore.
You can order Extended Long Term Support (ELTS) here: TYPO3 ELTS.
TYPO3 CMS offers a way for extension authors to provide automated updates for extensions. TYPO3 itself provides update wizards to smooth updates of TYPO3 versions. This chapter will explain the concept and how to write those update wizards.