That is absolutely the case. It's very important to remember that the Canada Labour Code establishes minimum standards and is always aimed at balancing employee and employer needs and interests. The employer is always able and has the discretion to provide more than the minimum standards provided in the code. There is nothing in the code that prevents them from doing that.
In the case of domestic violence leave, an employer can always provide leave for someone who they think would benefit from it as a result of their being a victim of family violence. They could always pay the leave, should they wish, and they can always provide more leave, if the employer wishes.