Increase the thickness of boxplot lines

x_font_size = 16;   %% new font size
line_thickness = 2; %% new line thickness

set(findobj(gca, 'type', 'line'), 'linew', line_thickness);
set(findobj(gca, 'Type', 'text'), 'FontSize', x_font_size);
set(findobj(gca, 'Type', 'text'), 'VerticalAlignment', 'top');