Best strategy for high W2 income earner?

[Andrew Zhang]

Hi, first time posting here. A little story about me is, I am unmarried, and late 20s. I was fortunate to make about $750k this year and next year the expected salary is $900k. I have a 1.2M house with 25%-ish equity, and no other assets. My yearly spending rate is low like 30K ish, besides the mortgage. I like my W2 job but I don't see myself keeping this high salary forever, so I am thinking of ways to create income streams. I've been reading posts here and was looking at low priced markets for cash flows, but even if I buy 10 of these and paid fully, it's nowhere near the income I am making. I also thought about buying more pricy homes in California and bet on the appreciation - but this doesn't seem like the most efficient way to use my liquidity. Maybe I should go into multi-unit homes? but I absolutely have no idea how to get started on this. My ultimate goal is to make 30k/month income apart from W2, but without working hard like STR owners.

Long story short, if you were making a high 6-digits a year, what asset would you buy to create incomes?