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As the other posters have already noted, Etherchannel sends a flow across just one link, so one flow will never obtain more than a single link's bandwidth.
Other flows, though, might be distributed between links, so your average bandwidth can exceed one link's bandwidth. Not all switches support all the same hashing algorithms, and of those which are supported on your device are best for you depends on the nature of your traffic. Generally, a hash that uses both source and destination IPs works well.
Even if hashing was completely random, remember there would still be the chance that multiple flows will use the same link. For example, 1st flow uses port channel, it selects link 1. 2nd flow now has a 50/50 chance of using (for dual port channel) either link 1 or link 2. If it chooses link 1, both flows share that link's bandwidth while all the bandwidth of link 2 goes unused. On average, for a dual port channel because of chance using already busy link, expect about 50% more effective bandwidth, not twice the effective bandwidth.
There are other technologies which will take advantage of all link bandwidth, such as packet-by-packet link sharing (normally very much not recommended), MLPPP or OER/PfR. Often the latter two are too slow for high bandwidth links or not supported on the platform.
