This video (in spanish) shows the operation of the new details block that WordPress 6.3 brings.
The details block has been known as the accordion block and it was necessary to install a specific plugin to have it.
Inserting the details block
To insert the details block in any page, post or template, go to the block inserter.
There you will see, in the “Blocks” tab and “Text” section, the option to add the details block.
Once the details block is inserted, you will be able to write the title where it says “Write summary”. And below, in the empty paragraph block, you can add any block (a paragraph, an image, etc.).