In case you know the possible formats, it's possible in the first 2 of the following ways. If you don't, 3rd may work. But i'm not sure whether it'll work always or not.
# sample data
x <- c("1992-04-30", "5/3/1992", "1992-04-30", "4/30/1992")
y <- c("%Y-%m-%d", "%m/%d/%Y")
# base R
as.Date(x, y)
#> [1] "1992-04-30" "1992-05-03" "1992-04-30" "1992-04-30"
# tidyverse
lubridate::as_date(x, format=y)
#> [1] "1992-04-30" "1992-05-03" "1992-04-30" "1992-04-30"
# special package
anytime::anydate(x)
#> [1] "1992-04-30" "1992-05-03" "1992-04-30" "1992-04-30"