CS 61A and 61B are not graded on a curve, so grades are based on how well you do, not how you compete with others. If you applied for EECS and get in, you won’t have to worry about grade or GPA to stay in the major beyond C / 2.0.
Also, while Berkeley CS 61A is over 1,000 students, the introductory CS courses elsewhere are large (e.g. over 700 for Stanford CS 106A and Harvard CS 50).