My iPhone battery is degraded

I see from the above that you have an 'earlier iPhone model’ If your phone is quite old, perhaps the battery is at the end if its useful life. Go to Settings > Battery > Battery Health & Charging and look at the Maximum Capacity; if it is 80% or below, it needs to be replaced by an Apple Store or Apple Authorised service centre. Don't be tempted to have a third-party battery fitted by an unauthorised technician. 

It may be time to buy a newer iPhone which will be able to run the latest iOS. 

Not knowing what model/year iPhone you have or where you live start here:

iPhone Battery Repair & Replacement - Apple Support

Some additional information for you:

Writing an effective Apple Support Commun… - Apple Community