is finding duplicates in excel still possible?

If you're on 365, =UNIQUE(A2:A500) in a spare column gives you the de-duplicated list without touching the original, which is safer than Remove Duplicates on a sheet you can't undo. For a count, =COUNTIF(A:A,A2)>1 next to each row shows TRUE on every repeat and you can filter on it.

Depends whether you want to see them or get rid of them, and the two live in different places. To see them: Home tab, conditional formatting, highlight cells rules, duplicate values. It just colours them in and changes nothing, which is the safe one to start with. To remove them: Data tab, remove duplicates, and only tick the columns that actually define a duplicate for you. With every column ticked a row has to match on all of them, so near-identical rows survive and it looks like the tool did nothing. If it genuinely finds none when you can see them with your own eyes, it's nearly always trailing spaces or numbers that got stored as text. Run a trimmed copy of the column and compare that instead.