core/api/admin/assets/js/form-select2.js

$(function() {
	"use strict";

    $('.single-select').select2({
        theme: 'bootstrap4',
        width: $(this).data('width') ? $(this).data('width') : $(this).hasClass('w-100') ? '100%' : 'style',
        placeholder: $(this).data('placeholder'),
        allowClear: Boolean($(this).data('allow-clear')),
    });
    $('.multiple-select').select2({
        theme: 'bootstrap4',
        width: $(this).data('width') ? $(this).data('width') : $(this).hasClass('w-100') ? '100%' : 'style',
        placeholder: $(this).data('placeholder'),
        allowClear: Boolean($(this).data('allow-clear')),
    });


});