Yes, a student from other state can appear in COMEDK and get admission in colleges like RVCE/BMSCE/MSRIT (given that he/she fulfil all the eligibility criteria).

COMEDK can be applied by any Indian students irrespective of state of domicile.

COMEDK is specifically for students residing outside of karnatka state, however, karnatka students can also apply for the same which increases the competition a bit, and they have a edge to appear in both KCET and COMEDK.

So, you should apply for COMEDK if you are willing to do B.Arch course.

ELIGIBILITY CRITERIA:-The COMEDK just came up with the new revised Eligibility criteria as follows-

• Revised eligibility for admission to No1st year of 5 year B.Arch degree course as approved by the central government has come into effect w.e.f academic session of 2019-2020 and the same is as under:

No candidate shall be admitted to the architecture program unless he/she has passed the examination at the end of 12th scheme of examination with 50% marks in physics, chemistry and mathematics and also 50% marks in aggregate of the 12th examination.

For more details visit:- https://www.comedk.org

Meanwhile, there are a lot of other colleges where you can do B.Arch ( architecture course)as:-

1)School of planning & Architecture , New delhi

2)Bit Mesra, Ranchi

3)CCA Chandigarh

4)JMI New Delhi

5)Jadhavpur university , Calcutta 

Good luck!!