How to create a Global Theme Style Kit
With Elementor version 2.9, the Theme Styles information is stored in Elementor's Default Kit. But what happens if you have more than one Kits in your site? Somehow you need to tell your WordPress site, which of the available Style Kits will apply by default globally. To do this, you need to define a Global Style Kit at the Style Kits Settings.
You can go to the Settings from the WordPress dashboard, under Style Kits > Settings.
Going to settings page from the Elementor Editor
In the Elementor Editor, trigger the right click menu and click the Style Kits link.
Under the Style Kit tab, you will find a text link under the Edit Theme Style Kit button, that prompts you to Set a Global Style kit. Click on the text link.
Choosing the Global Theme Style Kit
Clicking on the text link above, will take you to the Style Kits settings page.
At the Global Style Kits dropdown, you will find the available theme Style Kits.
The Default Kit that you will find in the dropdown is the default Theme Style preset that is generated by Elementor. Most likely, this is already configured as your Global Style kit.
Select the Theme Style Kit that you want to be global, and hit Save Changes.
Now, on every new page you create with Elementor, the Global Style Kit will already be applied.