how can I make this Headline?

Hi Galliaeran,

Give the Headline a class of grad-text. Adding Custom Classes: https://wordpress.com/support/wordpress-editor/adding-additional-css-classes-to-blocks/

Then, add this through Appearance > Customize > Additional CSS:

.grad-text {
background: -webkit-linear-gradient(#eee, #333);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

Reference to this code: https://cssgradient.io/blog/css-gradient-text/

Use two Headline Blocks. Place them inside a Container Block. Set the two Headline Blocks to display – inline. Then set the Gradient as I’ve mentioned but only to one Headline.

You can use the highlight feature of WordPress: https://share.getcloudapp.com/8LuYGqjP

Then, the code would be something like this:

.grad-text > mark{
background: -webkit-linear-gradient(#eee, #333);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}