I live in a country where children don't start school until 6.
I don't know about other preschool settings other than the specific one my DC attended; I know that it was free-flow free play there, and there was no instruction in reading, writing or maths, even in the final year. If they want to spend the whole day in the sand pit, or playing with dolls - or doing woodwork with saws and hammers and other proper tools - then they can.
However there were loads of special activities, projects etc in the pre-school year, culminating in a 3 day residential trip. The children certainly aren't bored - I'm always a bit
when people say their child was bored of pre-school and couldn't wait to go to school. Surely a 4 year old shouldn't be bored in a building full of age-appropriate toys and craft materials, populated by their peers!
My DC learnt so much in their first year of school - going from not being able to read and write, to reading and writing fluently. If you compared with children from an English yr 2, who have been at school 2 years longer, I don't think there would be much difference now - whereas back in September there was a big difference. They seem to have caught up in just one year. And they have a shorter day too - just mornings, 8-12 every day.
My youngest would be due to start Reception this September if we lived in England . I don't have any doubts about maturity, or academic readiness, or anything, I'm sure they would cope fine. But I am still massively relieved that they don't have to start school for another 2 years here, and can carry on spending the whole day just playing with their friends.