Today Samsung has decided to bring the 128GB and 256GB Galaxy S9 and S9+ to the USA. Both iterations will become available to pre-order tomorrow, on May 1. They will be released on May 18, exclusively at Samsung.com. We assume the company has surveyed the market and figured out there wouldn't be a lot of demand for these storage versions. Otherwise, selling them exclusively through its online store wouldn't make a lot of sense. Of course, you can still use microSD cards (up to 400GB) even with these models, for a possible maximum grand total of 656GB on your phone if you splurge and...
Source: https://www.gsmarena.com/samsung_officially_launches_128gb_and_256gb_galaxy_s9_and_s9_in_the_us-news-30784.php