Yes, scoring 308 in the JEE Advanced 2021 is enough for computer science in IIT Ropar because if a student is scoring such a high score, then definitely the rank would go below 1000. 

After attaining so many scores and ranks, a student will obviously get offers from the older IITs’ other branches. 

But still, if a student tends to join the IIT Ropar CSE branch then he/she is setting a trend to opt for the research-oriented Institute. IIT Ropar has the World Rankings and such students are the only cause. The student is making a great choice and