Spotfire can be styled and themed. You can access the features for doing this via the Visualizations menu, and then via the Canvas styling options. Best practices for styling and theming in Spotfire are documented here, along with some sample themed dashboards that you can download:
https://community.tibco.com/wiki/visual-design-best-practices-tibco-spotfire
Alternatively, you can click on this link:
If you download one of these dashboards, you can easily import the theme into your own analysis. You can also import a theme from an analysis file that's stored in the Spotfire library.
As with any styling or theming options in any tool, it's possible to make some really poor choices and produce something that looks horrendous! So, go carefully, and use best-practice choices and combinations of colors and fonts, and so on...