I am working in a place where a colleague has more or less elected herself to be leader, and is telling others what to do, and confusing everyone because she is giving us information that is conflict with our real manager.
Maybe the company needs leadership, but leadership is not telling people what to do.
Leaders set by example. Alexander the Great lead the calvary charge and was always the first over the wall in an attack (once he was stuck on a wall of a fort by himself while his soldiers struggled to get ladders up to join him).
To be a leader, do what you think should be done. Then others may follow you.
Leaders help others. Telling others what to do will only make them tell you to go stuff yourself. Rather a leader will be their to help. Support other people's ideas, rather than push your own. Tell the boss about the good things other staff are doing.
Leaders and managers make the mistake of thinking they should decide. Rather it is organisations that decide. No modern company works by individual decision making, rather it is collective (sometimes in committes, sometimes through a chain of decisions and recommendations). Give your manager proposals and ideas from which he can choose. Give him information, for example, Our sales in district X are low, here are suggestions (include the suggestions from other people).
In the end, don't be pushy and authoratarian. I think the worse the problem becomes, the less control you feel that you have, the more extreme your behaviour will become.
Remember the boss wants to believe that he is in charge. If you solve problems for your manager, then they will resent it. I have been employed on occasion to solve problems greated by my manager. Once I solve them I simply demonstrate that I am smarter than my manager and they get upset. If I don't understand or fail they are happy because they think they are smarter than me.
Rather than give solutions to your manager's problems, go to him with problems. Get him to solve your problems.
I worked with a guy who could convince other people his ideas were really their own, making them want to do it. I wouldn't be that extreme, but you should try and obtain as much input and ideas from your boss as possible (and then you can present your ideas as having come from him).