Yes, they'll easily escape from that container, and it will get worse as they get older. By the time they're four weeks old, they need at least 3/4 square foot floor space each.
I had a 16-18 inchs high cardboard divider in the spare bathroom where the chicks are. It lasted until they were old enough to get over it. Then, eventually, they became too heavy for it and flattened it out. I took it out as useless and in the way, so now they have the entire bathroom as their "brooder room", I'll just have to clean it later when they're in the coop in a couple of weeks.