Here is a response I received from Lexus 2 days ago.
Thank you for contacting Lexus, we regret to hear of your disappointment with not being able to add a tow-hitch on your 2019 UX 200 but do congratulate you on this purchase.
We are sorry; as you are correct we do not offer a tow hitch for your vehicle nor do not have any recommendations to a supplier or source that may.
However, you may wish to inquire with your local Lexus dealers Parts Department to determine if they offer such a product, as our dealers may carry items that extend beyond the Genuine Lexus Parts and Accessories line. Your local Lexus dealer may be able to provide you with a referral to a company who may offer the product.
That being said still please be aware that Lexus recommends using only Genuine Lexus Parts and Accessories for your vehicle. Non-Genuine Lexus Parts, or any damage or failures resulting from their use, are not covered by any Lexus warranty.
If we can be of further assistance, please feel free to contact us.