The RadEditor that ships on nearly every Sitefinity module is the same Telerik RadEditor you can buy on its own, but the toolbar Sitefinity exposes by default is a fraction of what the control can do. The toolbar is just an XML file, so you get to decide what shows up.
Load ~/Sitefinity/Admin/ControlTemplates/EditorToolsFile.xml and add the tools you want. If you want to see the full set the control offers, copy from ~/Sitefinity/Admin/ControlTemplates/EditorToolsFileAll.xml, which already has everything defined and ready to paste across.
Here is where I will take a hard line, because I have cleaned up the aftermath too many times. Do not hand non-developers the font size, font family, background, and text color pickers. It feels generous and it is a mistake. Editors who are not designers do not know what reads well in the context of your site, so they reach for five different font sizes and a red that fights your brand, and a few months later every page looks like a ransom note. The styling drifts page by page and there is no clean way to pull it back.
Give them constrained choices instead. Create paragraph items in the XML that wrap a selected block in a tag or class you control, then define what those look like in your site CSS. Now an editor picks something like "callout" or "lead paragraph" from a dropdown, and you decide how that renders everywhere it appears. They still get to mark up their content, you keep one consistent look, and restyling later is a single CSS change rather than a hunt through inline markup on a hundred pages.
The default toolbar is too thin to be useful and the full toolbar is too loose to be safe. The version worth shipping sits in between, and you get there by deciding which tools your editors have actually earned.