I see YouTube tutorials on STM32 boards and they use schematics to explain the internal connections of the board. However, I tried finding schematics and could not find any on the internet.
How to find the schematics of STM32H750b-dk boards?
Go to the ST website for the particular board and click on the CAD Resources tab.
E.g. https://www.st.com/en/evaluation-tools/stm32h750b-dk.html#cad-resources