Delay in charging my phone

It can happen that your iPhone is getting different times since charging is being simply affected by usage of your device. What I mean if you charging your iPhone and running some apps or playing games it will be longer to fully charge than the one which is just laying in standby mode.

Also if you enable Low Power mode or Airplane Mode(please note that networks and cellular will be off at this) it will speed up Your charging time.

and as it was suggested above higher wattage charger is the way to speed it up as well.

Then just charge the phone overnight, every night. You will have a fully charged phone in the morning, and it won’t matter how long it takes. As a free bonus, if you turn on iCloud Backup in settings you will have a new backup every morning also, so you will never lose more than one day’s data if the phone is lost, stolen or breaks.

The length of time to charge depends on what the charge level is before you start charging and what apps may be running in background while it is charging, as well as whatever apps or features you use while it is charging. If you use a USC-C power source it will reach 50% in 30 minutes. After that the charge rate slows down to avoid overcharging.

Here is a more complete explanation—>When to charge your iPhone or iPad - Apple Community

Is your friend using the same wattage charger?

Is your friend starting at the same charge level when initiating the charge?

How long does it take your friend’s phone to charge?

Perfectly normal.

It takes as long as needed to charge.

What do you mean why? A battery takes time to charge. It is a basic law of physics, that neither you or I can change.