inputEditDateFormat property
The date format in the input boxes when they are selected for editing. This must be a format that is recognized by JavaScript Date.parse.
This will only be used for inputs of type text. Since v8.2.3,
the input type is dynamically determined based on the granularity
of the inputDateFormat and the browser support.
API Docs: https://api.highcharts.com/highcharts/rangeSelector.inputEditDateFormat
Implementation
String? inputEditDateFormat;