It depends incredibly on locality, but yeah, some library positions do ask for minimum of a masters in library science (the relevant degree track!) or relevant experience (usually five years minimum). Admin, cataloging, things like department head, they're going to ask for a degree or a good bit of time doing the work; assistant, general librarian, stuff like that, can be less stringent.
Personally, I'm at a small, rural, public one, and basically got hired by default (my academic background's philosophy and accounting, not library science, ha) due to the then-director (genuinely one of the best in the state before they retired, for what it's worth) being more or less incredibly desperate for anyone with a liberal arts background (which, in fairness, philosophy is both close and the training for both my degrees have been pretty incredibly helpful even if it's not explicitly library science). Started as assistant, eventually trained in cataloging, which I've now been doing for the better part of a decade.
So like, yes? There's a specific academic background that's very highly prioritized with hiring. But also no. There's some discretion going on and specific local circumstances may mean folks without that specific background get hired, after which experience may substitute for the degree itself. If it's a very hard requirement where you're at, then it's more stringent than it is stateside, heh.