Undeclared at UCLA and finding a career path admitted fall 2019

Son has been admitted as undeclared physical sciences.
He wants to explore some form of engineering and business.
How easy is it to find out one’s direction at UCLA. We are concerned about the stories
regarding the difficulty in getting classes at UCLA. Is it a place where a student can explore prior to committing to a major?

@jototo He can take Engineering pre reqs like math and physics. Otherwise he would need to declare engineering. Since engineering classes are generally taken sophomore year on.