I'm 19, started making games when I was 10, began freelancing that when I was 17 and now pay for my uni accommodation by freelancing game development through sites like upwork.
My skillset is obviously quite hard to just pick up and run with so I wouldn't recommend trying to learn and freelance game development in like a year unless you're passionate, but there's plenty of other stuff you can do, just check out upwork where people are always asking for a range of stuff, programmers, artists, designers, video editors, musicians, writers etc etc. But the thing here is, you need to have a skill that you can sell.
If you choose to go this route you probably won't be making anywhere near as much money as you make landscaping in like 4 years minimum. You need to build up a portfolio and show you can actually do the work for prices you're after. The kind of people who also often use platforms like upwork have their limitations.
But here's what is good about it: Freelancing always has a client, unlike making a blog or a YouTube channel or product you're always working for a client who will pay for your product. Which is nice.
The usual stuffs, email list , pay ad , website promote affiliate stuffs , social media.