library(tidymodels)

tunable(
  linear_reg() %>% 
  set_engine("glmnet", dfmax = tune())
)
#> # A tibble: 3 × 5
#>   name    call_info        source     component  component_id
#>   <chr>   <list>           <chr>      <chr>      <chr>       
#> 1 penalty <named list [2]> model_spec linear_reg main        
#> 2 mixture <named list [3]> model_spec linear_reg main        
#> 3 dfmax   <NULL>           model_spec linear_reg engine