Elevation fullscreen

Leaflet.Control.FullScreen is for maps only.

But you can use detachedto display the chart in the map: [elevation gpx="..." !detached position=...].

I use detached but in this way I obtain a graph floating on the map, my goal is to have the graph in the default position (after the map, at the bottom) when not in fullscreen and at the bottom of the map when fullscreen.

This isn’t possible. You can show the chart inside or outside from the map (detached) and switch to show or hide the chart (chart). See the documentation.

Maybe your theme has an option to do so.

Unfortunately not, my theme haven’t an option for Leaflet Map I hoped to get this feature with your plugin, in any way thanks a lot

The way you want it, it won’t be possible.

But I have seen websites when answering support questions where the map and the chart have filled the entire area without using fullscreen mode. This is from theme.