As the AI Answer mentioned, the Surface Dock documentation doesn’t confirm that it works with an iPad. Since this is a Surface support forum, the help available here is mainly focused on Surface devices and accessories.
In this case, I’d suggest checking directly with Apple Support, since they’ll be better placed to confirm what the iPad supports. You may also find it easier and more reliable to connect the iPad straight to the monitor with a compatible display adapter.
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I hope this helps point you in the right direction.
Best regards.