There are a few different ways that you can block an app completely on your iPhone. One way is to go into the Settings app and scroll down to the General section. Tap on Restrictions and then enter a passcode. Once you have done this, scroll down to the Allowed Content section and tap on Apps. Here, you will see a list of all the apps that are currently installed on your device. If there is an app that you want to block, simply toggle the switch next to it to the Off position.
Another way to block an app is by using Screen Time. This is a feature that was introduced in iOS 12 and it lets you set limits for certain types of content or activities on your device. To use Screen Time, open the Settings app and tap on Screen Time. Tap on App Limits and then select Add Limit. Choose the type of content or activity that you want to limit (in this case, select Apps) and then select which apps you want to include in the limit. Finally, set how long you want to be able to use these apps for before they are locked out completely.
If neither of these methods work for you, there are also some third-party apps that can help you block apps on your iPhone. One popular option is Freedom (https://freedom.to/), which lets you block specific websites or apps for a set period of time so that you can stay focused on what's important. There are also some parental control apps like OurPact (https://ourpact.com/) which can help parents manage their children's screen time and prevent them from accessing certain types of content or applications altogether