Using an Iphone as a hand held GPS for hiking remote ares

Thanks for all the replies and info. I checked out OnX Hunt, Gaia GPS, AllTrails and USGS maps. Could not find from there web sites if the areas that I wanted where there without buying the subscription. The USGS maps were free and I found the trail I was looking for and for a one time use it looks fine. However if I were 20 years younger and was going to do a lot of hiking the Gaia and Alltrails were better but cost $19 -$29/year for a subscription.