Add custom regular expression pattern to SearchWP

searchwp-customizations.php

<?php

// Add custom regular expression pattern to SearchWP.
add_filter( 'searchwp\tokens\regex_patterns',
  function( $patterns ) {
    $my_patterns = [
      "/([0-9]{1,2}\\/[0-9]{1,2})/is", // Retain measurement details.
    ];

    // We want our pattern to be considered top priority.
    return array_merge( $my_patterns, $patterns );
} );