Sure! There are a lot of plants, etc. that contribute to the dark color of yolks. Free ranged chickens with lots of greens to eat generally have darker yolks. There are specific plants and spices you can offer a chicken to make their yolks darker.
Store bought egg yolks are often very yellow and quite tasteless whereas my free ranging hens eggs are bright orange like that and have a stronger taste. It depends on what they are eating! But there is nothing technically wrong with a yolk if it is anything between dark orange and pale yellow and a round plump shape.
Totally normal. A lot of people can be shocked when they have they're own chickens as the colour of their yolks are very often darker than the mass produced supermarket eggs. Those poor chickens live a cruel and unhappy life, with a very limited diet which keeps their yolks pale. As soon as hens have access to the outside and a varied food source, their yolks soon darken up!