Tabs
EuiTabs allow a size prop. In general you should always use the default size, but in rare cases (like putting tabs within a popover of other small menu) it is OK to use the smaller sizing.
Condensed tabs
EuiTabs allow a display prop. In general you should always use the default display. However, it is acceptable to use the alternative condensed display in situations where it is desirable to display a bolder, more compact and borderless tab interface (for use as primary navigation within your application or to establish a higher level hierarchy of tabs).
Tabbed content
EuiTabbedContent makes it easier to associate tabs with content based on the selected tab. Use the initialSelectedTab prop to specify which tab to initially select.
Dextrose
Controlled tabbed content
You can also use the selectedTab and onTabClick props to take complete control over tab selection. This can be useful if you want to change tabs based on user interaction with another part of the UI.