# summarize multiple columns
df %>% dplyr::summarize(dplyr::across(
  c(col1, col2),
  .fns = \(x) sum(x, na.rm = TRUE)
), .groups = "drop")

# summarize every column
df %>% dplyr::summarize(dplyr::across(
  .cols = dplyr::everything(),
  .fns = \(x) sum(x, na.rm = TRUE)
), .groups = "drop")

# summarize multiple columns with suffixes
df %>% dplyr::summarize(dplyr::across(
  .cols = c(col1, col2), .fns = list("sum" = sum, "mean" = mean),
  .names = "{.col}_{.fn}"
), .groups = "drop")