How to adjust the size of markers in legend box?

plotting

#1

When I change the marker size, it works well.
However, it does not change the size of markers in the legend box.

plot(
    xs,
    ys,
    titlefont  = font("Times new roman", 32),
    tickfont   = font("Times new roman", 24),
    guidefont  = font("Times new roman", 24),
    legendfont = font("Times new roman", 24),
    xlabel = xtitle,
    xlims  = xrange,
    xticks = xticks,
    ylabel = ytitle,
    ylims  = yrange,
    yticks = yticks,
    linewidth = 3,
    linealpha = 1.0,
    markershape = shapes,
    markersize  = 15,
    markeralpha = 1.0,
    color = colors,
    label = labels,
    size = (1200,800)
)
julia> Pkg.status("Plots")
 - Plots                         0.15.0