Legacy features are outdated, deprecated features and their use is discouraged. Currently the Legacy features are the following:
Accent colors
Accent colors are outdated, as they were created even before Elementor introduced Global Theme Styles. Feel free to use Style Kits Global colors to manage Color in your Elementor layouts.
If you install Style Kits on a fresh site, the Accent colors panel will not be available. The panel however will still be available in your existing sites.
Outer Section Padding and Column Gaps
With the introduction of Flexbox containers, Sections and Column gaps are slowly becoming deprecated. If your website still contains layouts with sections though, you will still be available to use Outer Section Padding and Column Gaps. If not, you can always hide them in Style Kits Settings (read below).
Show / Hide the legacy features in Style Kits Settings
Let’s say that you are starting a new project and you plan to work exclusively with flexbox containers. You may have no plans to use Sections and Columns anymore. In this case, to keep your Style Kits panel tidy, you may want to disable the legacy features.
You can do it so by going to Style Kits \ Settings and check the “hide legacy features” checkbox.
This will remove the features from the UI.
Heads-up! If you already use the above legacy features in your layouts, their data and settings will be maintained, and your existing pages will not be affected, even if you choose to hide them from Settings.