Customize Power BI Embedded Reports

Hi,

We want to customize our Power BI Embedded Reports to create our own style/visuals.

Here is an example from how it currently looks from inside Power BI:

Here we can only change data color for the graph line. We however, want to add a gradient to this specific line, like this:

We have found that the options to customize styles other than from the Power BI dashboard is limited. Is there any way we could modify the json or any other way achieve customization?