If i got qualified in IIT advanced examination , should i get the college and branch of my own choice? Plz answer

Hii

Once you qualify JEE advance, you need to appear in the councelling procedure which is conducted by JoSAA. You need to register for councelling and select the choice of colleges and courses.
Then a college will be alloted to you by the authorites based on your Secured Rank, preference and availability of the seat.
So, yes you will be allowed to make choices but you can not select the college of your choice, it will be based on your rank.
So the higher your rank higher is the chance of better IIT.
For example -
For IIT bhuwaneshwar you need to score around 5057 rank in JEE  Advance for civil engineering, 1404 rank for CSE, 3249 rank for electical engineering and so on.
Similarly in IIT Bombay, you require around 59 Rank for CSE, 1721 rank for Chemical engineering, 65 rank for electrical engineering and so on as per the previous year trends.

Hope this helps
Incase of doubt you can revert back.
Thanks!