Not all Xray packs are created equal. Some are obvious (you can see everything), while others are "stealth" (only highlight ores). Here are the best options for 1.12.
If you run a Minecraft 1.12 server and want to stop X-ray users, here is the only foolproof method: minecraft 1.12 xray texture pack
Do not rely on banning texture packs. A dedicated cheater will simply use a hacked client (like Wurst or Impact) which injects X-ray directly into the rendering pipeline—something a texture pack cannot compete with. Not all Xray packs are created equal
While modern versions of Minecraft (1.13 and up) introduced the "Flattening" (changing block IDs), 1.12 is still widely used by the community for three main reasons regarding Xray: Do not rely on banning texture packs
Do not use Xray on public multiplayer servers.
Let me be clear: Using Xray on servers like Hypixel, Mineplex, or any competitive Factions/KitPvP server will get you banned. Most 1.12 servers run "Paper" or "Spigot" with anti-xray plugins that either: