Is the i phone 8 plus go down water for one meter

No. No iPhone is rated for submersion. You should not put the iPhone in water. You should not be swimming with an iPhone either.

Water damage is not covered by warranty.

Read here for details: About splash, water, and dust resistance of iPhone 7 and later - Apple Support

To prevent liquid damage, avoid these:

• Swimming or bathing with your iPhone
• Exposing your iPhone to pressurized water or high velocity water, such as when showering, water skiing, wake boarding, surfing, jet skiing, and so on
• Using your iPhone in a sauna or steam room
• Intentionally submerging your iPhone in water

No. It is not waterproof. It is water and splash resistant. You, like many who come here, are confusing standardized testing methodology under controlled conditions with what the certification actually means in real world use.

Then he was either very lucky, or a catastrophic failure is about to happen to the iPhone.

The iPhone is not meant to be used under water.

eslambahy wrote:

Is iphone x go under water??!

No. No. No. No.

No. The iPhone X cannot go under water either.

No iPhone is meant to go under water.