Installing apps manually can be a great way to get access to a wider range of applications than what is available in the official app stores. Whether you're using an Android or iOS device, there are several ways to install apps manually. For Android devices, you can download the APK file (Android installation package format) and install it manually. To do this, open an Android file explorer application and navigate to the folder with the APKs.
Tap each one to install them, resulting in a screen similar to that of the installation from the other sources mentioned above. You may also need to give your browser permission to install apps if you're using Android 8 Oreo or later. If you've applied a jailbreak to your device, you can install almost any application you like, including applications to change the appearance of the interface, access the file system more easily, have applications superimposed on top of each other, and much more. However, it's important to be careful when downloading applications outside of your phone's app store as they can potentially harm your device.
For iOS devices, you can use a program called TestFlight to install applications that haven't been published in the Apple App Store. You can also download a large number of applications with your PC and then install them on your phone in one go. However, be sure to check and recheck the background of these applications and the background of the developers who create them before downloading them from the wild Internet.Remember to revoke permissions after installing a third-party application so that additional applications are not installed without your knowledge. In general, you should only install apps outside of your phone's app store if you have a very good reason to do so.