Creating geopackage layers as output with QGIS batch processing autofill option

Is it possible to use the Calculate by Expression tool to output geopackage layers. For example, with the batch option for the polygon to line function. With the following expressions I can create individual shapefiles or individual geopackage files but not layers in a geopackage file;

This creates a separate geopackage file for each layer;@project_folder ||'/' || @INPUT || '_line'

This creates a separate shapefile for each layer;
@project_folder ||'/' || @INPUT || '_line.shp'

However, I can’t find a way to output layers to the one Geopackage file. The Polygon to Line function seems to default to individual geopackage files if no extension is given. The following creates output – not individual layers but separate geopackage files;
@project_folder ||'/test.gpkg layername=' || @INPUT ||'_line
The file names end up like this;