Q:

How to change color in a specific time in css?

How to change color in a specific time in CSS?
For example, I want to change paragraph color in a specific time.
<style>
    p {
     color: black;
}
</style>
<p>I want to be white!</p>

Thanks. 
UPDATE:
I mean 1 second for example for this sentence

in a specific time

A:

with animation

 p {
   color: black;
   animation:animate .1s linear forwards;
   animation-delay:5s; /* text will be red after 5 second */
}

@keyframes animate {
  to {color:red}
}
<p>I want to be red!</p>

