Well, there is a population cost to building settlers in both games, but whether you will, net-net, lose population when building settlers in Civ VI will depend on your food generation rate in the city where you build your settlers (if time to next citizen roughly equals the time to build each settler, population will remain essentially static, just as in Civ V). Assuming you still lose one pop when buying settlers, Civ VI will be more costly than Civ V (in terms of population cost) if you habitually bought your Civ V settlers, rather than building them.
I'm hoping that one potential benefit of this change will be to eliminate the "exploit" where you could avoid losing population in a city that was under siege by shifting that city's production to a settler (which could be beneficial even if you had no plans to complete production of the settler once the siege was lifted).