All Bitnami native installers are completely self-contained and run independently of the rest of the software or libraries installed on your system. They won't interfere with any software already installed on your system, so everything you're already running will continue to work normally.
Having said that, there is not any automated way to upgrade PHP in the Bitnami X-Cart stack right now. We also want to let you know that we plan to move all our applications that support PHP 7 to this version in the near future but we can't provide you with an estimation.
You could run X-Cart on top of PHP by following these steps:
- Install WAMP stack with PHP 7
- Follow this guide
Please note that you'll need to configure your application manually.
Sorry for the inconveniences.