Parkinson’s disease makes it so difficult to use touchscreen iPad and iPhone

Hi, im trying to help my mom with her iPhone and iPad. She unfortunately has Parkinson’s disease and has severe hand tremors. Imagine trying to use an iPad or an iPhone with a really shaky hand. Does anyone know if there is an app or a setting in iOS that can help make the touchscreen less sensitive to a shaky hand? Has anyone else encountered this? My mom loves the devices because they make her feel connected, but it’s so frustrating for her to use bc of the very sensitive touch screens. Thanks for your advice!