I am not absolutely certain what the desired result is, however here is an illustration (although the online Run feature is not the best place to demonstrate it, since the plot areas are constricted, so experiment offline to get the best results) —
x = 1:0.1:10;
y = randn(size(x));
figure
plot(x,y)
grid
legend('y', 'Location','eastoutside')
title('Original')
figure
plot(x,y)
grid
legend('y', 'Location','eastoutside')
title('Repositioning Width')
% Fg = gcf;
% fpos = Fg.Position
% Fg.Position = fpos + [0 0 -50 0];
Ax = gca;
aipos = Ax.InnerPosition
Ax.InnerPosition = aipos + [0 0 -0.1 0];
aopos = Ax.OuterPosition
Ax.OuterPosition = aopos + [0 0 0.3 0];
.
