you cant samsung removed this on the EU S9 models.
you could search play store for a 3rd party app.
which is a shame we spend so much on the phones and they remove a needed function that blocks online fraudsters.
no samsung dont call them spammer they are Advertising customers.
by removing the blocker for text blocking samsung and google can allow spammers and advert companies
that are suppied by data via app store games and software to abuse and infect your phones.
we pay £1000 of our money for these phones for them to remove needed privacy services so they can make money
from the app companies.