what does apple limited warranty cover

An iPhone 6s was sold from September 2015 through September 2018.

The standard warranty is typically one year.

An AppleCare purchase can extend coverage, if that was originally purchased: AppleCare Products - iPhone - Apple

Here is how to check your coverage: https://checkcoverage.apple.com/

Warranty details: Apple One (1) Year Limited Warranty

The 32 and 128 GB models were discontinued 2 years ago now, and the lower storage models 3 years ago now. The warranty starts on the original date of sale from Apple or an Apple authorized seller, so the original one year warranty is almost certainly expired.

And the warranty does not cover any accidental damage, water damage, or purely cosmetic damage. A warranty covers defects in original parts or manufacturing processes.

Apple's Limited Warranty covers one year after it's purchase date from Apple or any approved retailer. This is from when the phone is new, not from when you purchase the phone.

As it is an Iphone 6s, this will no longer be covered by extended warranty as it is no longer sold. The typical warranty is 12 months as stated.

The Limited Warranty also does not cover accidental damage such as screen repairs. This is still charged at full fee. If you did purchase Apple Care+ screen placements cost around £25 (it might be different in USD) but this is just for future reference as it sadly won't apply to you this time.