Set symbol color from RGB values in attribute table is a popular idea for ArcMap to have:
The ability to set the fill colour for a symbol from RGB values stored in the attribute table of a shapefile/feature class.
Sometimes an attribute table contains three seperate columns - Red, Green and Blue - that define the fill color to be used to correctly symbolize a feature. Rather than manually going through each symbol it would be convenient to be able to specify the columns in Layer Properties | Symbology and the colors automatically render.
This is seeking precisely the same functionality except to have it available in ArcGIS Pro instead.
This has been marked by Kory Kramer as a Duplicate of Set symbol color from RGB values in attribute table. Please add your votes to that Idea, and if you are specifically looking for the functionality in ArcGIS Pro, add that to the Comments.