Link to the documentation: https://main-api.flutter.dev/flutter/material/TextField/minLines.html

If this is null (default), text container starts with enough vertical space for one line and grows to accommodate additional lines as they are entered.

This doesn't seem to be true. When maxLines is set to a non-null value, minLine is effectively set to the same value as maxLines. It seems the real meaning of null here is to defer to the maxLines parameter (which makes the default a bit strange, shouldn't the two parameters be orthogonal?).

This is hinted in the maxLines documentation: https://main-api.flutter.dev/flutter/material/TextField/maxLines.html

The input's height is large enough for the given number of lines. If additional lines are entered the input scrolls vertically.
const TextField(maxLines: 2)

but I wasn't able to find anything that directly spells out that interaction when minLines is null but maxLines is non-null.