Hello danielharrington06,
It sounds like you are interested in getting an Apple Watch and want to look into the Fitness app on your iPhone. However, you do not see this app.
Here are some resources that can help:
If you do not have an Apple Watch paired to your iPhone, it is the case that it would be expected behavior to not have access to this app as the Fitness app is to "get a comprehensive view of your total fitness from Apple Watch, including Activity History, Workouts, and Trends, all combined into one seamless view" as seen in Fitness on the App Store.
While an Apple Watch is required, a subscription to Apple Fitness+ is not. For more information on using the Fitness app check out the following resources:
For information on Apple Fitness+ and the compatible devices, take a look at Devices you can use with Apple Fitness+.
Hope this information helps.
Have a good day.