iPhone 6s Plus Replacement Battery

Hi,

I am using iPhone 6s Plus having a capacity of 2750 mAH battery. After a 3 years of period, the battery life got degraded and advised to replace at the earliest. When I searched in Amazon.com, I saw a new upgraded battery capacity of 3800 Milliampere Hour (mAh) was introduced replacing 2750mAH. Is this reliable to purchase and get it replaced in Apple authorized service centers? Kindly confirm so that I can order a 3800mAH battery. Thanks.

Regards,

Anand G