LA is hardly a center of record deals. Most of the music biz is based in Nashville, Tennessee now. LA is loaded with wannabe actors, not so much musicians (at least no musicians with enough knowledge of the biz to know they are in the wrong place).
Become an internationally renowned musician in UK - like Elton John, Beatles, and thousands more over the past 6 decades or more. Then if your agent gets a contract for a concert tour, performance, appearance in the US, the reputable US producer will apply for your P or O class temporary employment visa. You will be allowed into the US long enough to fulfill your contracted appearances.
Eventually, if you're famous enough, contracted to work in US enough, you might be able to get appropriate immigration visa & legal permanent residency in US. Like, for example, Celine Dion.
But you are NOT coming to US to get "discovered."