Combine the rice and water in the Instant Pot and secure the lid. Move the steam release valve to "Sealing" and select the Manual or Pressure Cook button to cook at high pressure for 4 minutes.
It will take the pot roughly 8 minutes to come to pressure before the cooking cycle begins. (In a 6 quart Instant Pot; a larger one will take longer.) When the cycle is complete, allow the pressure to naturally release for 10 minutes. The screen will read LO:10, and then you can move the steam release valve to "Venting" to release any remaining pressure.
When the floating valve in the lid drops, it's safe to open the lid. (See the video in this recipe post if you need a demonstration.) Remove the lid and stir in the coconut milk, cinnamon, vanilla, and maple syrup.
Remove the inner pot from the Instant Pot to help the rice pudding cool down faster. Serve the pudding with cinnamon, fruit, and an extra drizzle of maple syrup, if desired.
The leftover pudding can be stored in an airtight container in the fridge for up to a week. It will become very thick, and nearly solid, when chilled, so don't be surprised if you need to thin it out with water to serve it chilled, or you can warm it up (without adding liquid) so that the coconut milk will become runny again.