Hi there!

Thanks for your query.

Here is a sample code for you, please use it within the custom CSS:

.sppb-addon.sppb-addon-text-block .sppb-addon-content {
    letter-spacing: 2px;
}

You can change the spacing value as per your need.

Note: Path towards custom CSS: Extensions>Templates>Styles> Click on your current default template name then choose Template Options. Then find custom CSS within the custom code.

Best Regards