In Lightning Forms, you have the ability to create more than one New, Edit or Display customized form. However, the initial New, Edit, and Display customized forms are the primary default. They cannot be changed. Any additional forms created are non-default.
You can access the non-default forms from any page via a link. To obtain a direct link to the secondary form, click the secondary form's Edit Customization button, scroll to the end of the URL, and change "DesignMode=true" to "DesignMode=false". Copy and paste this updated URL in a different browser tab, and you should see your secondary form.
If it suits your scenario, you can also add this secondary form's URL as an Open Web Page action button on the original default first form.