You can adjust excerpt lengths and the ellipsis easily by adding the following code to the functions.php of your child theme and adapt it as you need:
PHP
function my_custom_excerpt_length( $length ) {
return 20;
}
add_filter( 'excerpt_length', 'my_custom_excerpt_length', 999 );PHP
function my_custom_excerpt_more( $more ) {
return '... read more';
}
add_filter( 'excerpt_more', 'my_custom_excerpt_more' );