The following works for me
julia> using StatsPlots
julia> plot(; title = "Test")
julia> boxplot!([1,2,3], label="a")
julia> boxplot!([1,2,3], label="a")
pkg> st StatsPlots Plots
Status `~/.julia/environments/plots1.0/Project.toml`
[91a5bcdd] Plots v1.35.4
[f3b207a7] StatsPlots v0.15.4