Editing Forms
Plumbersx theme comes with some forms that you can use to collect information from clients.
By default - We use popular Contact form 7 plugin. Because it provides full flexibility. However you are free to use your own choice of plugin if you want to. And just use that plugin's shortcode instead. ( As seen below )
The blue background bar code in above screenshot, is the Shortcode that plugin provides you, in order to use this form anywhere on any page. Almost every form plugins in WordPress ecosystem provides shortcode. So if you use any other plugin, you can still grab the shortcode provided and paste it on the Shortcode area on left panel when editing the page with form.