Hello aspirant.

You can do architecture after diploma in Civil engineering, providing that you have cleared the Backlog in that particular semester including your final year semester exams. You can sit in architecture paper/exam, only after you have cleared your backlog in that particular semester exam.

You can do architecture course after completing diploma course . Today an architecture related course in India makes a lots of sense. The course you should go for is Architecture Engineering. It is related to the design of bridge, multipurpose building, industrial area, residential area etc.

Further, to know more about the architecture engineering, you can follow the below mentioned link to know more about it in detail : https://www.careers360.com/courses/architecture-engineering-course

I hope that this will help.