The only thing that appears to work is to set flex-wrap: wrap; on the container and them somehow make the child you want to break out after to fill the full width, so width: 100%; should work.
If, however, you can't stretch the element to 100% (for example, if it's an ![]()
), you can apply a margin to it, like width: 50px; margin-right: calc(100% - 50px).