How to increase the character height with no change of the body of the character?

on Font Creator
How can I increase the height of the character without changing the size of the character itself?
The image below shows what I mean.
size1.jpg

Switch to point mode, select the points, and move them up together, holding the shift key to maintain the horizontal position of the nodes.
Adjust selected nodes.png

I don’t want to change the character’s size, I just want to change the size of the rectangular frame around it.
I don’t know how to do this.
Thanks for your response

For what purpose would you use this?

I need it for mathematical purposes, so I need symbols that are sometimes smaller than other symbols, but at the same time I need all symbols to have a rectangular frame of the same height. By the way, the picture that I attached is just a random example and the character in it is not one of the characters used

Add a rectangular contour at the Y-max point and delete two or three nodes to leave a contour with one or two nodes. The validation tool can be used to clear them before exporting the finished font.
Contour with two nodes.png

I tried to do what you mentioned but it didn’t work for me
When the verification tool deletes the remaining two points, the frame returns as it was
Maybe I didn’t implement the method properly

That is the expected behaviour. Verification will remove contours with one or two nodes.

I will try until I succeed
Thanks for your help Bhikkhu