Yes, you can.
LandingRabbit doesn't require an existing website to get started. You can create pages from scratch and publish them with us in a custom domain.
In the first screen, click "...or create a new website from scratch" instead of entering a URL.

In the next screen, you'll be asked to:

In the description, you can share, for example:
This helps LandingRabbit understand your business so it can generate relevant content for your pages.
After you hit Next, you'll pick a color scheme for your pages.
You have two options:

These colors will be used across all your pages to keep things consistent.
Once setup is complete, you can share what page you'd like to create.

LandingRabbit will generate the page based on your topic idea using the colors you chose during signup.

From there, you can edit the content, adjust the look and feel, and publish your page using your custom domain with LandingRabbit.