The Samsung Galaxy S9 and S9+ are billed to receive the One UI 2.1 update
Samsung unveiled One UI 2.1 with the Galaxy S20 phones a while ago. Since then, the company has sent out the update to its older phones, starting with the Galaxy S10 range, and down on to the Galaxy Note 10 Lite. There's been doubt over the chances of the company's 2018 flagships receiving the One UI 2.1 update, but there now seems to be light at the end of the tunnel.
A Samsung chat rep has confirmed that the Galaxy S9+ is billed to receive the One UI 2.1 update. Seeing as the S9+ and the smaller S9 are a pair, it's safe to say that the regular S9 will also get the update—if its bigger sibling does. Sadly, the chat rep couldn't provide any dates.
While customer support has proven to not be a good source of information on software update policies, the fact that recent information indicates the Galaxy Note 9 will receive the update lends credence to the idea of the S9 and S9+ also getting the update. They are, after all, of the same generation. In any case, One UI 2.1 will be the last major update the phones get.