Dear Sir,
Good day! Thank you for posting to Microsoft Community. I am happy to help you.
Based on your description, I understand that you are trying to create a form in Microsoft List and in the form, you are unable to see branching option in the form.
May I know if my understanding is right? If so, I have tasted on my side (for both online and Desktop apps) and found branching option on the left side bar. However, If you can’t see it by default, please click on any question or option in the form > Click on “...” > add branching. branching option will immediately showed up.
I hope this will help you to solve your issue. To know more about branching please refer to this link Use branching logic in Microsoft Forms - Microsoft Support.
I appreciate your patience and understanding and thank you for your time and cooperation.
If the scenario above is not consistent with yours, you can also post back and point that. I am always here to help you.
Best Regards,