The version you're referring to, "YouTube 13.42.6 IPA," suggests you're looking for a specific version of the YouTube app, possibly to access features available in that version or to install it on a device that doesn't support the latest versions of the app through the App Store.
Search for YouTube in the App Store; the tweaks will trigger a prompt to "Download the last compatible version". Sideloading the IPA File Archive Sources: You can find historical IPA files on Internet Archive or legacy community threads on Reddit's r/LegacyJailbreak Sideloadly Youtube 13.42.6 Ipa Download
If you want, I can:
Jailbreak Tweaks: For a more stable experience on iOS 9, tweaks like App Admin or Checkmate, Store! allow you to download the last compatible version directly from the App Store if you have previously "purchased" the app on your Apple ID. The version you're referring to, "YouTube 13
(e.g., changing "13.42.6" to "16.02" or higher) to restore partial functionality. Safe Sources for Legacy IPAs allow you to download the last compatible version
