This recent Business Insider article details how to download Google Maps information to your phone’s local storage, so you can use Maps even when offline or when your phone is unable to get a signal: https://www.businessinsider.com/how-to-use-google-maps-offline .
When I travel, I always have Google Maps save a map of the area I’m travelling to. It’s not always possible to have a working cell signal – in flat Illinois where I live, it’s easy to have cell signal all the time. When I travel to more mountainous regions such as Colorado, I often lose signal due to mountains and hills between me and the signal tower.