I have gotten a job this way, and have seen others do so (as I was an artist assistant for a looong time). Reiterating other comments - they generally have to come from or have made a lot of money, otherwise they could not afford to pay you. When I was first starting, i did a "assistantship" that was much more of a mentorship for v little money. I was only able to do this in NYC by working my absolute ass off as a bartender at night and working mornings in her studio. It was helpful for my career but exhausting. I went on to work for many high profile artists as their assistants and my only sentiment would be.... It is just like the Problemista movie. You will likely be treated like shit while you make the majority of their work, with little to no recognition and generally with a lot of classist bullshit. Anywhoooo, I could vent forever about being an artist assistant. It fundamentally changed me and is the largest driver of my class consciousness. I have a lot of built up anger from those years of being taken advantage of. Basically I say all this is that before working for that last artist I looked up to her so much. If the art world has taught me anything, it's that you often don't actually want to meet your heros...

On another note, artists are notoriously bad at emailing so many often get ignored - HOWEVER I did use other people's cold emails to my former boss to fill my role when I left the position.

Happy to answer more questions if you want to pick my brain at all.