how to change the siblings in child css without using parent code example

Example 1: css select all siblings after element

/*To match to any sibling element after the selector on the left,
  use the tilde symbol '~'. This is called the general sibling combinator. */

h1 ~ p {
  color: black;
}

Example 2: other children than first css

div ul:nth-child(n+2) {
    background-color: #900;
}