We have written all our components as functions so far in this series. However, you can also use classes to create components in React. In fact, classes were preferred for crating complex...

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A component is considered to be mounted when it is first rendered to the DOM. Mounting and unmounting are part of a component's lifecycle. There are special methods called and which run after a component is mounted and unmounted respectively. We can set up a timer here that will update the state of our component every two seconds.

Learn React 18: Writing Components as Classes

Yeah possible but why?
<a href="https://react.dev/reference/react/PureComponent#skipping-unnecessary-re-renders-for-class-components" target="_blank" rel="noopener nofollow">https://react.dev/reference/react/PureComponent#skipping-unnecessary-re-renders-for-class-components</a>
Even official docs warn you about pitfalls and recommend going with functional component, react is just an API to make “magic” happen, so if they encourage you to use functional components you probably should go this way as docs says :)

Isn’t the point of the updates after 16.8 to move into more functional components ? Why would anyone learning react now learn class based ?