Wick size is set by how much wax the flame has to melt, and everything else is an adjustment to that. In order of how much each factor matters:
Jar diameter, by a long way. The flame has to produce a melt pool that reaches the glass. Diameter is the whole job: a taller jar of the same diameter needs the same wick, which surprises people.
The wax. Soy, paraffin and blends have different melt points and different viscosities, so the same wick behaves differently. A chart for one wax does not transfer to another.
Fragrance load. Fragrance oil thins the wax and adds fuel, and above about six percent it starts genuinely changing the burn. This is real and it is smaller than people think - usually one wick size, not three.
Colour. Dye is the least important, and pigment-heavy colours can clog a wick. Liquid dye at normal amounts is close to irrelevant.
Wick material. Cotton, cored and wood all behave differently and are not interchangeable by number.
So the practical starting point: pick the wick series for your wax, look up the size for your diameter, and treat that as the middle of your test range rather than as the answer. The chart is a starting point that manufacturers publish knowing you will adjust.