Hi there,
This looks like the best solution: https://wordpress.stackexchange.com/a/168763
For example:
add_filter( 'single_template', function( $single_template ) {
if ( in_category( 1 ) ) {
$file = get_stylesheet_directory() . '/single-cat-1.php';
if ( file_exists($file) ) {
return $file;
}
}
return $single_template;
} );
You’d have to update the 1
to the ID of your category, and single-cat-1.php
to the name of your file, which would have to be in your child theme.