You can turn on or off Location Services on iPhone at any time you want and here’s how (here, I’m using iPhone X (iOS 13.3)):
Steps to enable or disable Location Services
Tap Privacy which you can find beneath Battery.
Hit Location Services at the top.
Now, hit the toggle beside Location Services at the top.
If you are disabling, you can see a pop-up at the bottom. Read the message in it, and if you’re okay with that, tap Turn Off option.