Yes, you can place the legend in the empty tile by specifying the tile number.
Here's a demo -
%Plotting random data in the first 13 tiles
tiledlayout(7,2);
for k=1:13
nexttile
plot(sort(rand(10,1)), rand(10, 2))
end
%Define Legend
l = legend({'First line', 'Second line'});
%Changed the tile of the legend to the empty one which is 14 here
l.Layout.Tile = 14;
