On macOS, it is possible to select items such as checkboxes or even dropdown lists by pressing the spacebar when the item in question is highlighted (usually with a colored box around the item). The ability to highlight them (usually by default or by using the tab key) can be enabled with the Full Keyboard Access setting in System Preferences > Keyboard > Shortcuts (this feature can also be enabled by pressing ControlF7).
I went to this website and tried to check out all of the fonts, which is done by selecting the font from the dropdown list. I wanted to quickly cycle through all of the fonts. I tried using the down arrow key to select the next list item when the list was highlighted.
However, when you press the down arrow, the list "pops up"; you then need to press down and then press enter (or space) in order to select the next item. This effectively means that, to select the next item in the currently highlighted list, you need to perform three keyboard actions, which makes it extremely cumbersome to cycle through all of the items.
I tried pressing the down arrow key while holding shift, alt, command, control, etc. hoping one of those would be a secret shortcut to select the next list item without, but using these modifies did not change anything.
Is there a good shortcut to select the next list item?