I want to use more graphic options in Dashboards.
one of them is 'Scatterplot'.
Could ESRI make all the graphic options in the Arcgis software platform available in Arcgis Dashboards?
This actually belongs in the Dashboards Ideas space. You should re-post there so that users can up-vote it and it can be logged as a suggested improvement to dashboards.
Like @jcarlson said, I believe that posting this in Dashboards Idea space would be the best course of action.
In the meantime, ArcGIS Instant Apps has the Chart Viewer template where you can view and interaction with charts created in the New Map Viewer (this includes scatter plots).
You could even try to embed this Instant App into an ArcGIS Dashboards (using the Embedded content element) as well.
If you have ArcGIS Insights, you can also create a scatter plot there, share it as a page and embed it as well.
Hope this will be helpful to your workflows.
If this answer solved your question, please mark it as "Accept as Solution" to help others who have the same question.