Problem in my IP address

When I write what is my ip in google it shows same ip on al devices even iphone and pc

example: I wrote what is my ip in google and its say: 20.24.129.21
when I write from iphone or another computer it say: 20.24.129.21

That's because you are seeing the IP address of your modem and not the IPs of the devices on your local network. This is normal.