Samsung intends to showcase the upcoming Galaxy S9 and S9+ for the first time at CES in January, according to a new rumor allegedly originating from "someone briefed on the company's plans". It's unclear how much information about the devices will be shared on that occasion, however, since Samsung apparently still plans to hold an official unveiling event in March. The Galaxy S9 and S9+ will have the exact same screen sizes as their predecessors, and very similar looks. 2018 will be an iterative year for the Korean company's flagships, so you shouldn't expect a new revolutionary design....
Source: https://www.gsmarena.com/samsung_to_show_galaxy_s9_and_s9_at_ces_in_january_bigger_model_gets_more_ram_and_dual_camera-news-28386.php