On your iPhone or iPad, open the Google Maps app . Tap your profile picture or initial Settings Navigation. Under “Map display,” turn Show speedometer on or off. Tip: If the Speed Limits feature is available in your location, you can turn the speedometer on or off by tapping Speed Limit / during navigation.
https://support.google.com/maps/answer/9356324?hl=en&co=GENIE.Platform%3DiOS

