Hi @Boban J., yes exactly based on cookies.
We drop a persistent cookie to track new vs returning. If we are just now creating the persistent cookie then we know they are new, if we are reading already the persistent cookie and have seen it in Dynatrace, Dynatrace knows this is a returning user.
Bit more detail is available here: https://www.dynatrace.com/support/help/shortlink/c...
Hope it helps you out!