Technically, "conversion" is a bit of a misnomer. You aren't changing the code; you are the contents.
While an simplifies the distribution of large Android apps by bundling APKs and OBB data together, it isn't natively supported by Android's default installer. To install these files without a dedicated third-party app, many users turn to an XAPK file to APK converter online . Understanding XAPK vs. APK Xapk File To Apk Converter Online