I searched YouTube and many other platforms but not able to find any source of information for creating expandable menu. once clicked on a button other buttons should move down. PFA images.

2 Answers
2This is a good reference: 1
The collapsible menu you want is called as ‘Accordion’. I did something like this before with the help of this Thread:
https://forum.unity3d.com/threads/accordion-type-layout.271818/