https://michaelsoriano.com/how-to-create-an-advanced-search-form-for-wordpress
https://www.wpbeginner.com/wp-tutorials/how-to-create-advanced-search-form-in-wordpress-for-custom-post-types
https://www.wpbeginner.com/plugins/how-to-add-ajax-taxonomies-filter-in-wordpress-search
if your having trouble following the code this plugin might help you:
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