For some drones, absolutely. Some drones have hardware/software limitations to be aware of, but the general theory is simple enough, more mAh = more flight time. Software limited machines will actually lock the drone, or refuse to boot up, if the 'official' battery is not installed, so you're not likely to get a bigger battery on your DJI drone, for example. Otherwise, please be aware that different batteries may offer different voltages. This is most evident in the racing community, where you'll hear about batteries called 1S, 2S and up to 6S, usually. The over-simplified explanation is that each 'S' is worth 3.7 Volts. You will absolutely burn out a 1S rated drone if you install a 6S battery. Assuming your drone can handle the full range of voltages, a 1S battery is worth about 750 mAh of power, a 6S battery is usually worth about 2,000 mAh, but we've seen them 11,000 mAh and larger. Again, please just be aware of the voltages, but the more mAh in the battery, the long it should last.