You can get code snippets for React or HTML and also configure many different aspects of embeds using the Embed Snippet Generator. The code snippet is automatically updated with the changes you make in it.
Here is how you can access it.
Click on three dots of the event type and click on the option
Embed
Configure as you require and then
a. Copy the HTML code snippet
or,
b. Copy the React code snippet
What can you configure
Size of embed
Theme
Toggle event type details
Brand color
Layout
Floating button text
Floating button position at the bottom
You can also configure all the custom CSS variables supported by cal.com app. Here is a list of all the supported CSS variables.
Also, here is the codeSandbox demo for a configuration where the look and feel of the embed is changed.