Automation usually created to be triggered by some record (new or changed). But of course, you can insert script step, which will process all table and the trigger might be a schedule for daily or weekly use.
You can do this by scripting Extension (somewhere in Examples you can find a script to remove duplicates), you can use Deduper Extension or you can do it manually, create new linked field (to a new table), copy-paste whole primary field there, and then add data you need by lookups. In duplicated records, all data will be present, so to avoid repeating, you can use rollup ARRAYUNIQUE(values).
It's for one-time action. If you need to do it from time to time, use Extension.
Or you can check it once and then setup automation to check each new record for duplicates.
