Scatter plot, trend line and R-squared value

Hello,

I'm performing a scatter plot on Power BI Desktop with X axis, Y axis, Legend and Size values.

I noticed that into analytics panel the trend line is not available (I can select only X-Axis and Y-Axis constant line, min and max line, average line, symmetry shading and ratio line).

If I remove size into scatter plot the trend line becomes available.

Is there any possibility to show the trend line even if I add size info scatter plot ?

In addition is there the possibility to show the R-Squared value when the trend line is shown?

Thanks in advance for the collaboration

Elisa