The default X5S is having a 15mm focal length. In Pix4Dcapture that the default X5S parameters that are taken into account when planning a mission.
If you decide to change that lens to use a 25mm focal length, then you will have to implement it as a custom camera in the iOS version of Pix4Dcapture to still have the correct overlap. Note that we can not guarantee that it will work as we do not support this kind of configuration.
However, we assume it may work but if you can set a timelapse in the native drone application and set a custom camera in Pix4Dcapture. We don’t have user feedbacks about this type of configuration and we will be glad to get some so don’t hesitate to share if it works for you or not.
Then, if you can fly with your X5S, for the same GSD than the X4S, you will be able to fly higher and then cover a bigger surface.
We have reason to believe that whatever rolling shutter distortion that may be present in images captured by your drone will be marginal and should have little to no effect on your project results. To limit it if occurring, we suggest flying slower and/or higher to reduce the amount of linear rolling shutter distortion that is present in your images.