What does the datasheet and/or Reference Manual tell you ?
See also:
AN5105 Getting started with touch sensing control on STM32 microcontrollers
AN3960 Guidelines for ESD for touch sensing applications on STM32 MCUs
AN3236 How to Increase the number of touchkeys for touch sensing applications on STM32 MCUs
AN4310 How to choose the sampling capacitor for touch sensing applications on STM32 MCUs
AN4312 How to design surface sensors for touch sensing applications on STM32 MCUs
AN4299 How to improve conducted noise robustness for touch sensing applications on STM32 MCUs
AN4316 How to tune touch sensing applications on STM32 MCUs
via: https://www.st.com/en/microcontrollers-microprocessors/stm32l476zg.html#documentation
