I am a premed, and I got admission from UCLA for Biophysics major. I appreciate it if anyone can let me know how is this major like, and how possible it is to maintain a good GPA for this major. Do they scale down?
It’s possible to get good grades in any major…if you work hard.
I doubt that UCLA “scales down” grades in any major…whatever that means.
Be prepared for a lot of hard work and competition – all pre-med specific courses will be difficult because of the competitive nature of pre-med programs/students. As for “is it doable” – obviously for many students it IS. Otherwise the major wouldn’t exist. 
But we have no way of knowing if it’s “doable” for you specifically.
On your other thread…you say…pre-dental…and you are trying to decide between UCLA and Cal.