The overall design feels extremely modern and, as for influences, all that I can pinpoint is the embroidery, which is clearly inspired by Art Nouveau design, which is fitting for the character, as it has been a constant influence since Episode II
See it here
As for accessorizing, since your outfit is already tonal, you can opt for a different-colored handbag if you would like: harmonious colors featured in this article, like butter yellow, white and light pink are all great options
The short answer: no, elopement dresses do not have to be white
Because royal blue stands out, its perfect for events where you want a bolder looksuch as weddings, parties, or presentations where you need to make an impression