There are any number of hardware or software expanders available. The software ones are typically far more flexible. However, an expander can never truly undue the compression/limiting applied to modern recordings. You will be able to gain a few dBs in dynamic range, but it's unlikely that it will sound any more natural than before processing.
Can we increase dynamics?
It might be a silly question, but since recordings have compressed dynamics (to work on average systems) is there anything to expand dynamics back to normal (or at least close) - either in form of hardware "expander box" or software I could batch convert my files with?