https://stackoverflow.com/questions/46765197/how-to-enable-image-upload-support-in-ckeditor-5

Yes, image upload is included in all the available builds. In order to make it work, though, you need to configure one of the existing upload adapters or write your own. In short, upload adapter is a simple class which role is to send a file to a server (in whatever way it wants) and resolve the returned promise once it's done.

You can read more in the official Image upload guide or see the short summary of the available options below.

Custom upload adapter
You can also write your own upload adapter which will send files in the way you want to your server (or wherever you like to send them).

See Custom image upload adapter guide to learn how to implement it.

An example (i.e. with no security built-in) upload adapter can look like this: