finding 6 or more duplicates

welcome to the forum, Irhawkins. 1 way:
select the range you want to apply to (say from A2:A100)
go to Home -> Conditional Formatting -> New Rule -> Use a formula to determine which cells to format -> Format values where this formula is true:
=COUNTIF(A:A,A2)>6

format a colour. you can then apply Autofilter & filter those with colours