Hello @sai1 and welcome to the community,
You didn't tell about the board you are using? is it a custom board (a board you have developed )? or an already board available on the market?
If you are talking about STM32H757 Reverdi board, according to their site it is using RVT70HSSFWN00 display selectable from TouchGFX designer:

But if it's a custom board, there is no selection of the display, you need to start from scratch from CubeMx tool: configuration of the MCU, the LCD, the external memories and add TouchGFX middelware. Refer to TouchGFX Documentation.
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