Autocomplete – change minChars

<?php

/**
 * Add to your (child) theme's functions.php
 * Replace "YOUR_AC_NAME" with the actual facet name
 */
add_filter( 'facetwp_render_output', function( $output, $params ) {
    $output['settings']['YOUR_AC_NAME']['minChars'] = 2;
    return $output;
}, 10, 2 );