This is still a relevant topic. I was able to finally center some value from a Choice column using this CSS, which applied globally to ALL fields. After trying to target fields individually with custom classes, I just added this CSS and shifted by focus to adjusting other fields that were not impacted by this CSS.
.k-state-default input, span.k-picker-wrap.k-state-default,
.fd-form .k-dropdown-wrap .k-input, span.k-dropdown-wrap.k-state-default {
text-align: center !important;
justify-content: center !important;
}
You can see the "After" illustration is still not centered but a lot closer. I will work on getting it perfect. This kind of sloppy look drives me bonkers.
As for your question, the search terms are key to finding anything, anywhere. I searched various strings for hours such as "Center CSS", "Center Choice", "Align-Center". After so many attempts, I searched "Dropdown" and found this post. It is maddening to not have the right words when you're not sure what you're looking for