Hi,@FarazI995
Thanks for posting your question in the Microsoft Q&A forum.
Based on your description, you don't want to use mail flow or third party paid software to add email signatures to all your users.
I checked the official Microsoft documentation and unfortunately, the only official method provided is mail flow.
The features you want may not be available at the moment.
If my answer is helpful to you, please mark it as the answer so that other users can refer to it. Thank you for your support and understanding.