How to show as list

whenever gst category changes i want to populate the sales type with specific values as dropdown

frappe.ui.form.on('Sales Order', {
    custom_gst_category: function(frm) {
        // Update custom_sales_type field options based on custom_gst_category value
        if (frm.doc.custom_customer_location_type == "India") {
            if (frm.doc.custom_gst_category == "Registered Composition" ||
                frm.doc.custom_gst_category == "Registered Regular") {
                frm.fields_dict['custom_sales_type'].set_input("B2B AMC INDIA\nB2B SPARES INDIA\nB2B CONSUMABLES INDIA\nB2B PRODUCT INDIA");
            } else if (frm.doc.custom_gst_category == "Unregistered") {
                frm.fields_dict['custom_sales_type'].set_input("B2C AMC INDIA\nB2C SPARES INDIA\nB2C CONSUMABLES INDIA\nB2C PRODUCT INDIA");
            }
        } else if (frm.doc.custom_customer_location_type == "International") {
            frm.fields_dict['custom_sales_type'].set_input("SALES INTERNATIONAL");
        }
    }
});