The following MWE shows the list piece by piece and each item is alert when displayed and back to normal when the next item is displayed.
How can I add more default overlay specifications to the itemize list? Say, make the text bold and alert as it appears and return to normal when the next item is displayed?
\documentclass{beamer}
\begin{document}
\begin{frame}
\begin{itemize}[<+-| alert@+>]
\item Apple
\item Peach
\item Plum
\item Orange
\end{itemize}
\end{frame}
\end{document}
As said in the comment, you can start from Changing the font for "alert" in beamer. In this answer, I provide an example in which the modifications done to the font are local just to the itemize environment. Indeed, one might want just to modify the font aspect for a particular list.
Code:
\documentclass{beamer}
\usepackage{lmodern}
\begin{document}
\begin{frame}
\begin{itemize}[<+-| alert@+>]
\setbeamerfont{alerted text}{series=\bfseries, size=\Large}
\item Apple
\item Peach
\item Plum
\item Orange
\end{itemize}
\uncover<+>{This is another \alert<.>{alerted} text but is not more in bold, since the change has been done locally to the itemize environment.}
\end{frame}
\end{document}
Result:
