To use font awesome icons as CSS content code add font style using custom css properties in font awesome 6.And manually add the font-style and font-weight css properties in font awesome 5
Font Awesome 6 Icons available for pre-order. And Who ever having active font awesome subscription at the time of release will get access to font awesome 6 icons.
This post contains free font awesome icons class list names with their CSS content value codes & step by step tutorial to use font awesome icons in HTML pages.