How to add custom block/pattern under query-loop block.

[emson-softound]

want to change the content generated by post-template block inside query loop with custom block design of my own.
How to achieve this.?
(or)
I want to create my own custom block that contains query-loop and inside the query-loop my own html/php code.
i came across this
#43449
https://developer.wordpress.org/block-editor/how-to-guides/block-tutorial/extending-the-query-loop-block/
do i have to create two custom blocks to achieve.
one for query control variation.
one for the post design.