@magdalenab My daughter started attending center based care at 18 months, and they moved her into a preschool classroom at 3. But they didn't have a super academic curriculum. I didn't see her learn to read or write in any meaningful way until last year, when she was in first grade. It was a Montessori inspired school, so as others have said, there was an emphasis on doing things like zipping a jacket, opening a snack, toileting independently, etc.
She's in second grade now, and fortunately doesn't have homework, but I am constantly gobsmacked by what she's learning. She's easily a year ahead of where I was as a kid, just because the curriculum moves faster these days. They're starting to jump into division and fractions, which is crazy to me, but she seems excited.