Hi, and welcome.
You'll find this in the forecast package..
install.packages("forecast","fpp")
library(forecast)
#> Registered S3 method overwritten by 'quantmod':
#> method from
#> as.zoo.data.frame zoo
library(fpp)
#> Loading required package: fma
#> Loading required package: expsmooth
#> Loading required package: lmtest
#> Loading required package: zoo
#>
#> Attaching package: 'zoo'
#> The following objects are masked from 'package:base':
#>
#> as.Date, as.Date.numeric
#> Loading required package: tseries
data(ausbeer)
fcast <- forecast(ausbeer, h = 4)
autoplot(fcast)

Created on 2020-02-18 by the reprex package (v0.3.0)