No, The website custom theme or any 3rd party theme will not affect the mobile app theme. The Mobile app is the native app. The App has its own theme.
In the mobile app, the color combination, app name, app logo, images, font etc. will be changed as per the customers’ business requirement.
Also, if you want to change the design /layout of the current mobile app theme then it will also be done through customization (a paid service).
To know more please feel free to contact us here – https://mobikul.com/contact/