Forest: Global settings for far out children

Question

I want smaller font size for all levels except the far out children (in the example below, everything except I saw Jane.) How do I do that with the forestset?

\documentclass{article}
\usepackage[linguistics, edges]{forest}
\begin{document}
\begin{center}
    \begin{forest}
    forked edges,
    [S
        [subject
            [pronoun [I]]
        ]
        [predicate,before computing xy={s/.average={s}{siblings}}
            [verb [saw]]
        ] [object
            [noun
                [Jane.]
            ]
        ]
    ]
    \end{forest}  
\end{center}
\end{document}

Answer 1

With use of the forestset:

\documentclass{article}
\usepackage[linguistics, edges]{forest}
\forestset{  % <---
  my tree/.style={for tree={forked edge,
                  where n children=0{font=\large} % <---
                                    {font=\small} % <---
                           }
                 }
          }% end of forestset

\begin{document}
\begin{center}
    \begin{forest} my tree % <---
[S
    [subject
        [pronoun 
            [I]
        ]
    ]
    [predicate,before computing xy={s/.average={s}{siblings}}
        [verb 
            [saw]
        ]
    ] 
    [object
        [noun
            [Jane.]
        ]
    ]
]
    \end{forest}
\end{center}
\end{document}

Answer 2

\documentclass{article}
\usepackage[linguistics, edges]{forest}
\begin{document}
\begin{center}
    \begin{forest}for tree={font=\tiny},where n children=0{font=\normalsize}{},
    forked edges,
    [S
        [subject
            [pronoun [I]]
        ]
        [predicate,before computing xy={s/.average={s}{siblings}}
            [verb [saw]]
        ] [object
            [noun
                [Jane.]
            ]
        ]
    ]
    \end{forest}  
\end{center}
\end{document}