First, realize that "Los Angeles" (the county; not just the city) is a sprawling area which extends from the harbor of Long Beach and the Pacific Ocean shores of Santa Monica & Malibu to the edge of the mostly desert "Inland Empire" to the east and through the magnificent San Gabriel Mountain Range to the high desert area of Lancaster to the the North, plus the nearby Disneyland area in Orange County to the south.
So if you simply go to work each day and return back to your home afterwards, you'll be missing the chance to meet a lot of people who are very active outdoors, all over the county.
Virtually all ethnicities have established neighborhoods where they predominate the local population, so if you are from Central or South America, Canada, China, Japan, Vietnam, The Philippines, Eastern or Western Europe, the Middle East, Africa or virtually any other place in the world, you can fairly easily locate expats from your home nation who will speak your native language and be able to help guide you during your first days in "La-La Land".
I know we don't talk about religion on this website, but you will certainly be able to find a religious organization which communicates in your native language and works to preserve the culture of your native land. Spanish-speaking Catholic parishes, Greek and Russian and other Eastern Orthodox Christian Churches abound in the region.
If you are less religiously inclined, you will find many opportunities to attend various types of philosophical and spiritual gatherings, sometimes through extension education courses in the inexpensive community college network.
Opportunities to volunteer are virtually countless. If there is a cause which is important to you, there is some kind of group which would welcome you with open arms. If the environment or homelessness or social justice are important to you, you will quickly make friends with fellow workers toward a common goal.
If all of that seems to be too much, then simply spend time where other people spend time. If you have a child, take them to a local park, and both you and your child will be likely to make new friends on the playground. If you have a dog, take it for a walk where other dog walkers go. The beach areas are great areas to meet people, especially if you play volleyball or fly a kite or lift weights or shoot hoops (basketball).
Also look for a meetup that interests you, in one of the local papers or on the internet.
Finally, know that people who live in L.A. like to travel to all the cool places in Southern California, so you should too. Take a train ride from Union Station (across from Olivera Street) south to San Diego or north to Santa Barbara. Drive or take a quick, inexpensive flight to Palm Springs, or even Las Vegas (which can be easily reached in a day).
You might not actually meet a new friend as you first travel around the region, but you will begin to appreciate what locals love about "SoCal", and when that happens, you will be building common interests which will draw you and your future friends together.
Have fun!
Gordy