Yes, any fare you find on OTAs can be replicated in GDS.
But keep in mind that OTAs can offer lower prices, since they make their win by issueing lots of tickets and a travel agent needs to add their own markup as a service fee to make a living.
Also the more tickets you issue, the better the prices airlines offer you. So while expedia group can get a nice discount from airlines, someone who makes <1mill$ revenue with an airline won't get the same discounts.