Creating a custom multistep form with WordPress involves using a plugin to create the form and customizing the design to suit your needs.

Install and activate the Gravity Forms plugin.
Create a new form by going to Forms > New Form in the WordPress dashboard.
Add your form fields to the form by dragging and dropping them from the right-hand menu. For a multistep form, you may want to group related fields together on separate pages.
Add a page break field between each group of related fields by dragging and dropping it from the right-hand menu. This will allow you to break the form up into multiple pages.
Customize the appearance of the form by going to the Form Settings tab and selecting the Appearance tab. Here, you can choose a theme, customize the colors, and add custom CSS to make the form match your website’s design.
Set up form notifications and confirmation messages in the Form Settings tab.
Add the form to your website by using the shortcode provided by Gravity Forms. You can add the shortcode to a page or post by using the shortcode block in the WordPress editor.

You can use it to collect information from your website visitors and generate leads for your business.