It is specifically stated that a shinobi can increase his or her chakra volume via training. It is stated in the manga, anime and databooks that Chakra is created when two other forms of energy, known collectively as one's "stamina", are moulded together. Physical energy (身体エネルギー, shintai enerugī) is collected from each and every one of the body's cells and can be increased through training, stimulants, and exercise. Spiritual energy (精神エネルギー, seishin enerugī, English TV: Mental Energy) is derived from the mind's consciousness and can be increased through studying, meditation, and experience. These two energies becoming more powerful will in turn make the created chakra more powerful. Therefore, practising a technique repeatedly will build up experience, increasing one's spiritual energy, and thus allowing more chakra to be created.
so any character who has large chakra reserves developed it by either increasing the physical or spiritual energy or both. through physical training such as running, push ups etc etc or doing mental training such as studying, reading, meditating etc etc.
on top of that another important factor is chakra control which is important because all though its possible to maximize the amount of chakra a shinobi has. there are still some limitations based on genetics. as such this is why someone like kakashi has average levels of chakra volume. but i also believe that its possible to break the limit to a degree. one such way is to seal chakra away for later use. this will grant you a higher level of standing chakra volume and in turn it will allow you to train harder and develop chakra beyond the limits of your genetics IE tsunade was born with chakra of a high calbre and volume because she is senju/uzumaki. but the seal on her fourhead clearly allows for even greater chakra volumes