Developer Zhouwei Zhang revealed on Twitter that he was able to change the iOS system font without jailbreaking.
To do this, he used the CVE-2022-46689 exploit found in iOS 16.1.2 and older OS versions. It allows applications to execute arbitrary code with kernel privileges.
Zhang noted that the change only affects some of the text on iOS, as other parts of the system use different fonts.
To try the font changer application yourself, you will need to download the entire source code from GitHub and compile the program through Xcode yourself, or manually sign the IPA file with a developer certificate.