It's a great idea, if your goal is to destroy your iPhone so you can buy a new iPhone. But if you don't want to destroy your phone, it's a very very very bad idea.
This link from Apple contains the following --> About splash, water, and dust resistance of iPhone 7 and later - Apple Support
To prevent liquid damage, avoid:
- 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
- Operating your iPhone outside the suggested temperature ranges or in extremely humid conditions
- Dropping your iPhone or subjecting it to other impacts
- Disassembling your iPhone, including removing screws
Minimize exposing your iPhone to soap, detergent, acids or acidic foods, and any liquids — for example, perfume, insect repellent, lotions, sunscreen, oil, adhesive remover, hair dye, and solvents. If your iPhone comes into contact with any of these substances, follow the instructions to clean your iPhone.