I think it depends on the school. Our first only started school in September, so it's still fresh in the mind.
The teacher did a visit to both DD's nursery and to our home so that we could meet her and so that she could meet DD in surroundings familiar to her. That way it wasn't so daunting for DD and that the teacher wouldn't be a strange face on the first day of school. This was in mid June. The home visit was more for the first timers. The expectation for younger siblings was that the parents would have already met the teacher. Our DS will be going September 2026, so we'll see what happens next year.
They then had a stay and play at the end of July so that they could meet a few of their new classmates, and see their classroom. The class was divided in half and the visits staggered.
Finally, at the start of term, they had a staggered start:
Monday was a teacher training day.
Tuesday, half the class attended for half a day.
Wednesday, the other half attended for half a day.
Thursday, the first half attended for a full day of school.
Friday, the second half attended for a full day of school.
The following Monday they were all in together for the full day.
As it was such a short settling period we just ran with it and took annual leave. As a PP says though, you can send your child full time from the get go.