The "better" universities, many of which are not in the RG group (examples could include St. Andrews, Bath, Lancaster, Surrey) will be grade based offers.
Every Uni does provide details of its typical offer requirement for every course it offers so there is lots of information readily available. Taking as an example Chemistry:
Cambridge - RG Uni - ranked 1st for the subject (although its part of NatSci there) requires A A A
Durham - RG Uni - ranked in top 5 for subject, requirement AAA, with Maths along with Chemistry both required, although neither has to be the A
Bath - not RG - in top 10 for subject, typical offer AAB
Nottingham - RG Uni, still top 20 for the subject - typical offer AAB - ABB
Sussex - not RG, still top 20 for the subject - typical offer ABB
UCLAN - not RG, mid / lower 30s for subject - requirement 280 UCAS points
Northumbria - not RG, towards lower end of subject ranking - requirement 300 UCAS points, including a specific 100 pts for Chemistry
Average achieved UCAS points (so includes everthing that would be counted by UCAS eg 4th AS, General Studies / Critical Thinking A2, EPQ etc)
Cambridge : 663
Durham : 571
Bath : 452
Nottingham 454
Sussex : 402
UCLAN : 324
Northumbria : 329