After Diploma in Architecture, you can join the Bachelor of Architecture course by giving the NATA examination. But on qualifying this examination, you will be able to take admission in B.Arch but it won't be a lateral entry course as a result, you won't be able to get a reduced course time.

Now if you want to switch branch from Architecture to Civil Engineering, then you can get the BTech Lateral entry course, in which you will be provided admission directly to the 2nd year of BTech.

For more information regarding NATA consider the link below:

https://engineering.careers360.com/exams/nata

I hope this helps. Wish you a great day!