Use a legitimate resource pack or texture pack that highlights ores
Enable the resource pack in Minecraft settings
Use spectator mode if you are in a world where cheats are enabled
Use creative mode to inspect underground areas in a private world
Use mods that are allowed on your server or single-player world
Use caving, branch mining, and strip mining to find ores normally
Use night vision and full-bright settings to improve underground visibility
Check your server rules before using any client modifications