Ooh, that sound fund! Was it How to Disappear Completely and Never Be Found
by Sarah Nickerson? (I haven't read it, just got sucked into a Google rabbithole!)
That would definitely appeal to me as a child. But I think my favourite fantasy was Pippi Longstocking. The idea of having no parents around (sorry mum and dad, no offence!! -- just wonderful to have that freedom), so many gold coins that you can buy all the sweets in the shop, and the strength to lift a horse.
I just found out that "the inspiration for her father, Captain Ephraim Longstocking, came from the real life Carl Emil Pettersson, a Swedish sailor who became king of Tabar Island in Papua New Guinea after he was shipwrecked in 1904. He married the local king's daughter, and they had nine children."
https://en.wikipedia.org/wiki/Carl_Emil_Pettersson