una/studio/template/agents_agents_form_object_select.html

<div id="bx-agents-agents-form-object-cont" style="overflow:visible;">
<select id="bx-agents-agents-form-object" name="form_object" class="bx-def-font-inputs bx-form-input-select">
    <bx_repeat:form_objects>
        <option value="__value__" <bx_if:sel>__sel__</bx_if:sel>>__title__</option>
    </bx_repeat:form_objects>
</select>
</div>
<script>
    $('#bx-agents-agents-form-object').select2({
        templateResult: (state) => {
            return $(`
                <div class="bx-form-object-wrap">
                    <div>
                        <div class="bx-form-object-text">${state.text || state.id}</div>
                    </div>
                </div>
            `);
        },
        templateSelection: d => d.text,
        tags: true, // allow custom inputs
        createTag: function (params) {            
            const term = $.trim(params.term);
            if (!term) return null;
            return {
                id: term,
                text: term,
                title: term,
                value: term,
            };
        },
        placeholder: "Select or type a value"
    });

    $('#bx-agents-agents-form-object').on('change', function () {
        const value = $(this).val();
        const sUrl = sUrlRoot + "grid.php?o=__grid_object__&a=get_form_inputs&csrf_token=" + window.glGrids.__grid_object__._sCsrfToken;
        $.post(sUrl, {form_object: value}, function(oResult) {
            if (typeof(oResult.code) !== 'undefined' && oResult.code == 200) {
                const newData = oResult.form_inputs;
                const select = $('#bx-agents-agents-form-input');
                select.empty();
                Object.values(newData).forEach(input => {
                    select.append('<option value="' + input.name + '">' + input.name + (input.caption.length > 0 ? ' - ' + input.caption : '') + '</option>');
                });
                select.val(null).trigger('change');
            }
        }, 'json');
    });


</script>