Apex Legends is not an OpenGL-based games, and the option in Nvidia Control Panel that's titled "OpenGL rendering GPU" have literally no effect on the game.
The only reason "OpenGL rendering GPU" is even mentioned as a placebo solution from what I can tell is because non-Nvidia Optimus users browsing their Nvidia Control Panel trying to locate the setting that controls whether a game is using the iGPU or dGPU of an Optimus platform, and that's the only setting they find that might be relevant and so they refer to it.
Actual owners of Nvidia Optimus-based platforms will know that the setting to change is actually called just "Select the preferred graphics processor for this program" and is available above the scroll list in Manage 3D Settings, same as in the linked source. This options is not, however, available on non-Optimus platforms, and so nobody with a desktop will have that option present on their system.