How do you know a vpn actually works. is there any way to test it?

I’m not a IT guy so i just know the basics, i do know a bit how a vpn works but idk if it can be tested or how it can be tested.
Do you guys wanna make sure it works before you use it? Or is it a matter of trust.

Turn off your VPN
Go To https://whatismyipaddress.com/ this will show you the IP address you are connecting from

Turn on your VPN
Reload https://whatismyipaddress.com/
If it is different then your VPN is working, if it is the same then your VPN is not working

For what is worth you can usually just search “what is my IP address” in your favorite search engine and it will show you the IP address you are connecting from

I stopped getting dmca letter