I don't know anything about Mattvei's book so this is not a comment on that.
When I was first starting out as a freelancer I bought several similar books (about creativity, business, self-employment, etc.). In my defense I will say that only one of them had "six-figure income" in the title.
There is a joke about how the only people who get rich off of "how to get rich" books are the people who write them. There are some good ones (the less extravagant the hype, the better the book, usually, IMO). I think they are more good for big-picture stuff -- getting the right attitude (usually some combination of "no pain no gain" and "believe in yourself"), understanding how to reach out to people (talk about what you can do for them, not what they can do for you), how to set goals, network, etc. I don't know of any that will directly get you a job.
The only ones I remember that seem like they could be good across (almost) all fields of work are the "guerrilla marketing" books. Otherwise, it really, really depends on what you want to do. Trying to make a plan without setting goals first is like trying to build a house without a foundation. Really take the time to brainstorm out what you want to do.
As far as the advice that you get from those books, I'd say try (almost) anything twice. Push yourself out of your comfort zone. And then if it doesn't work or you hate it, drop it -- find the stuff that works for you.
One more thing: anything written before 2020 or so, keep in mind that the whole remote-work landscape changed with Covid so what you're reading may or may not hold.
¡Suerte!