Vivo V11 Pro is made of industrial grade polycarbonate material.
Yes, Vivo V11 Pro does have the 3.5 mm headphone jack.
Yes, Vivo V11 Pro does have the OTG support.
Yes, Vivo V11 Pro does have FM radio support.
The Vivo V11 Pro is a solid all-rounder at Rs. 25,990 and offers better value than the Oppo F9 Pro (Review), but for a bit more money. Think of it as a Vivo X21 with a bigger battery and better front camera, but at a much more reasonable price, which is a good recipe.