There is currently no Joomla 4 version of Components Anywhere.
With Components Anywhere you can place components anywhere in your site. You can place components within articles, inside modules, or even inside 3rd party components and template overrides.
For instance, you have a form component - that does not come with its own module version - and you want to display the form in a module. With Components Anywhere, you can do so.
You can place components literally anywhere you want, wherever you have the ability to enter text.
You only need to place a simple tag like this to place a component where you want it to show: