Enzo Le Fee scored twice, while Chris Rigg, Timur Tutierov and Tom Proctor also found the net.
Le Bris gave 23 players valuable minutes, changing his entire team at half-time before Leo Hjelde suffered an injury.
“We gave 45 minutes to each team who have been connected with the training workflow,” Le Bris told media after the match.
“It is important to experience game situations, and to be fair, York played good football this afternoon.
“They tested our defensive structure, and in the first half we were able to score four goals, so it was good.
“We will go through this pre-season with different issues and dynamics to manage. We don’t want to rush the game time for our players.
“For the players who experienced the World Cup, we will have to build the first layers without much game time at the beginning, with only short periods on the pitch.
“When we face Lens and Rennes, I hope we have the full squad available.
“It is important to build a squad ready for both competitions,” he continued.
“The Premier League will be our main target, so it is important to strengthen the group with three or four core players.
“We need to strengthen the foundations and, after that, we will need a full group to manage the demands.”
Sunderland will now continue preparations with a 12-day tour of the United States, facing Liverpool, Leeds United and Wrexham.