Can I use a 18w charger for iPhone XS?

You can use any Apple or Apple-Approved charger, regardless of its ratings, as long as the connectors fit without forcing. The charge rate is regulated by the phone, not the power source. So you could even use a 61 watt or 90 watt USB-C MacBook charger without any problem.

Thanks Zahidch07,

Yes, you can use that charger without issues.

Cheers.

Hi Zahidch07,

It looks like you're wondering about charging your iPhone. If that's correct, check out this resource.

Charge and monitor the iPhone battery

You can use that charger without issue.

Cheers.