In addition to simplicity, a great app design must be mobile-first. The majority of users interact with apps on mobile devices, so ensure that the design is optimized for various screen sizes and resolutions. Navigation should be seamless with clear categories and quick access to the most-used features. Focus on minimizing the number of steps required to perform tasks, keeping actions as straightforward as possible. Furthermore, consider accessibility—make sure the app is usable by people with different abilities. Incorporating elements like voice commands and adjustable font sizes can improve inclusivity. Try using maybe free mockups
https://illustrarch.com/articles/42569-how-mockups-empower-apps.html for your app and this can help