Hello
you need to set the static front page template first

Step 1: Go to Dashboard >> Pages >> Add New, enter page name and select template as Home Page Template from Page Attribute
Step 2: Publish this page

Now set it as front page from Home Page Setting
Step 1: Go to Dashboard >> Settings >> Reading, select home page as a front page
Front Page Home
Step 2: click on save changes after this and the demo template will be available on the front page

please refer to our full documentation on the link below for more details on how to customize the theme
https://luzukdemo.com/demo/pet-clinic/documentation
Thank you