Unfortunately, the iPhone 8 Plus isn’t waterproof, but it is water-resistant.
If a Phone is Waterproof, it means water cannot pass through or damage the device, whereas water resistance refers to the device being able to resist a certain amount of water but not entirely. Also, take into consideration resistance can decrease due to normal wear and tear.
An IP water resistance rating is normally used to measure how much and how long the device can be submerged in water before it gets damaged.
The iPhone 8 Plus has a rating of IP67 under IEC standard 60529, which means it can be in a maximum depth of one metre of water for up to 30 minutes.
However, if your iPhone 8 Plus comes into contact with a liquid apart from water, such as coffee, tea, fizzy drinks etc, carefully rinse it off with water and wipe your device with a soft cloth.
Before you attempt to remove excess water, make sure your iPhone is dry. Also, do not try to dry the device with a heat source or put anything into the lightning connector as this could damage it.