Hey Shan.

You can apper for the architecture entrance exams conducted if you want to study architecture aftet class 12. Some of the most popular exams are

NATA

National Aptitude Test In Architecture

Online & Offline

JEE-Main

Joint Entrance Exam – Main (AAT)

Online & Offline

HITSEEE

Hindustan Institute Of Technology And Science Engineering Entrance Exam

Online

CEED

Common Entrance Examination for Design

(post graduation in design  )

Online & Offline

(conducted by IIT BOMBAY )

GAT

Gitam Admission Test

Online

AMUEEE

Aligarh Muslim University Engineering Entrance Exam

Offline

BSAUEEE

BS Abdur Rahman University B.Arch Entrance Exam

Online & Offline

JEE-Advanced

Joint Entrance Examination  AAT (Advanced)

Online & Offline

KIITEE

Kalinga Institute of Industrial Technology Entrance Examination

Online

Some state level architecture entrance exams are

JNTUPACET

Jawaharlal Nehru Technological University Planning And Architecture Common Entrance Test

Offline

State(All India)

UPSEE

Uttar Pradesh State Entrance Examination

Offline

State(Uttar Pradesh)

KCET

Karnataka Common Entrance Test

Offline

State(Karnataka)

WB-JEE

West Bengal Joint Entrance Examination

Online

State(West Bengal)

IPUCET

Guru Gobind Singh Indraprastha University Common Entrance Test

Online

State(Delhi)

TANCET 

Tamil Nadu Common Entrance Test

Offline

State(Tamil Nadu)

Hope this helps. Please feel free to respond and ask further questions. 

All the best.