how to change color of each letter of <p> with just css

I am trying to change each letter styles but I'm restricted from using javascript and without using span for each letters , I searched got some pseudo nth-letter but this not working , I know this type of question asked before but the restrictions force me to add this question.

please give some suggestions , it is really helpful

.change:nth-letter(3)
{
color:red;
font-size:20px;
}

<p class="change"> Color </p>

Solution

This is a hack that uses:

a monospace font so that each letter has a uniform width
inline display so that the width of the container is as much as its text
uses experimental background-clip: text to clip the background on to the text
uses a linear-gradient to color each letter

See demo below:

.change {
  font-size: 20px;
  font-family: monospace;
  display: inline;
  -webkit-background-clip: text;
  background-clip: text;
  color:transparent;
  background-image: linear-gradient(to right, black 40%, red 40% 60%, black 60%);
}

<p class="change"> Color </p>