Engineering management is still a somewhat esoteric discipline. I’ve never met an engineering manager who had formal management training, and most people have the position thrust upon them and figure it out day-to-day.
That said, there are some excellent reads out there that will make you feel less like you’re losing your mind in the first year.
My first recommendation to newly-minted managers is The Making of a Manager by Julie Zhuo. It’s not specifically about engineering management, but it is the best general introduction to the kind of problems you’ll be encountering when everyone starts looking to you for answers. Julie starts out from the beginning—of suddenly being thrust into a position of leadership and not having a clue what’s expected. The advice is free of jargon, down-to-earth and very practical. It should give you the confidence that what you need to learn is not some crazy new ideas, but a structured way of helping people. The People—Purpose—Process trifecta is one I still refer to frequently.