@Muhammad Zeeshan, Thanks for posting in Q&A. From your description, it seems you want to install one application during Autopilot enrollment. If there's any misunderstanding, feel free to let us know.
To deploy app during Autopilot, please ensure the app support device install context.
Then contact app developer to see if the app has the silently install command which can install without user interaction. If yes, you can firstly add the app via Intune win32.
https://learn.microsoft.com/en-us/mem/intune/apps/apps-win32-add
And then deploy it to the Autopilot device group to install the app during Autopilot enrollment ESP phase device setup.
https://learn.microsoft.com/en-us/mem/intune/enrollment/windows-enrollment-status#esp-tracking
In ESP, there's a setting "Block device use until these required apps are installed if they are assigned to the user/device:", you can set the app under select to ensure the selected-apps must be installed before users can use their devices.
Hope the above information can help.
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