Accuracy check:
iOS 12.5.7 was released in January 2023 for older devices (iPhone 5s, 6, 6 Plus, iPad Air 1st gen, iPad mini 2/3, iPod touch 6th gen). As of my knowledge cutoff and current security research, there is no publicly verified, working jailbreak for iOS 12.5.7, with or without a PC.
unc0ver: A widely used semi-untethered jailbreak that supports a broad range of iOS 11 through 14 versions. How to Jailbreak Without a PC jailbreak ios 12.5.7 no pc
iOS 12.5.7 runs on the arm64 architecture (64-bit). On these specific devices, Apple implemented a security mitigation known as KASLR (Kernel Address Space Layout Randomization) and a strict read-only kernel memory structure. Accuracy check: iOS 12
Leo toggled Airplane Mode on. He cleared his RAM. He held his breath. How to Jailbreak Without a PC How It
The short answer is yes. However, there are nuances. You cannot use modern one-click apps like ZJailbreak or TweakDoor (which are often scams for this version), but a legitimate, semi-untethered method exists entirely on-device.
Run the Jailbreak: Open the tool and tap the "Jailbreak" button. The device will likely reboot or respring. You may need to run the app again and tap jailbreak a second time if the icon for Cydia doesn't appear immediately.