JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/flatpickr/dist/flatpickr.min.css">
<script src="https://cdn.jsdelivr.net/npm/flatpickr"></script>

<input type="text" class="datepicker" name="datepicker" value="">

JavaScript

flatpickr('.datepicker', {
  mode: "range",
  altInput: true,
  altFormat: "M j",
  dateFormat: "Y-M-d",
  defaultDate: "today",
  maxDate: "today",
  locale: {
    rangeSeparator: '-'
  },
  onChange: function(selectedDates, dateStr, instance) {
    let today = new Date().toLocaleDateString();

    selectedDates.forEach(d => {
      if (d.toLocaleDateString() === today) {
        d = 'Today'
      }
    })
  }
});