My iPhone 7 battery health is 72% now so do I need to get replace with a new one ? Please suggest

Start here: https://support.apple.com/en-in/iphone/repair/service/battery-power

That's up to you. You can either live with shortened battery life, pay to replace the battery, or buy a newer model iPhone.

If your battery health was recently much higher but then quickly dropped to 72%, it most likely means that your battery is damaged.

My iPhone 7 battery health is 75%,so I want to exchange battery . I want know about iPhone 7 battery mah and what’s cost of exchange battery