For Android you'll probably need root access (unless the app developer has opted in to loading your user-imported certificate authorities). For iOS this should be easier.

However, many apps apply cert pinning in production builds, which will require tools like Frida to disable them, which in turn requires root access/a jailbreak to function.

Alternatively, you could pull the apps from your phone without root (at least on Android), patch the most obvious cert pinning out (usually in the network manifest file) and install the new version.