The only built-in styling features were added in Gravity Forms version 2.7, but these features are only available when using the block editor.
If you’re not using the block editor, there are a few other options. Now most page builders don’t have an element or widget for using the builder to style the forms either.
You can find a detailed styling guide provided by Gravity Forms support documentation to help you create some custom CSS to style your forms.
However, if you’re not up to the task of writing CSS, you can use one of the plugins below: