Is your TV a Roku Plus, Select, or Pro Series TV? If so, you can find information on the mounting screws here:
How to choose a wall mount for your TV | Official Roku Support
If your TV was made by TCL, Hisense, onn, etc., you'd have to check their websites for information.
I've never received mounting screws with a TV, but every wall mount I've purchased came with a plethora of different sized screws to cover every possibility.
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