The ability of a registered LLC to purchase goods in bulk from an online platform and export them using tax exemption will depend on various factors, such as the nature of the goods, the tax laws of the jurisdiction where the LLC is registered, and the tax laws of the jurisdiction where the goods are being exported.

In general, LLCs may be able to purchase goods tax-free if they are purchasing them for resale. This can depend on whether the LLC has a valid reseller certificate or sales tax exemption certificate, which may be required by the online platform or seller. However, if the LLC is exporting the goods, it may be subject to export laws and regulations, which can vary by jurisdiction.

It is essential to seek the advice of a tax professional or attorney who is knowledgeable about the tax laws and regulations that apply to your specific situation. They can help you navigate the complex tax laws and regulations and ensure compliance with applicable laws and regulations.