How do I bypass the battery using command keys on MacBook Pro 2017

It's unclear why the command keys are specified as the mechanism to disable/bypass the battery - there are many features and functions on your Mac that aren't implemented with the command keys or any of the modifier keys for that matter. For instance you can hold Caps Lock to switch languages or hold a letter to get it's dialects (i.e. press and hold U for ü as in Über)

That said, command keys or not, you cannot bypass the battery to only run on AC; period. This core question has been asked already:

• Force USB C MacBook to run off AC power
• Is there a way to bypass charge a 2019 MacBook Pro?

It basically comes down to how the MacBook was engineered - since the battery is no longer removable, it must be managed by the system and in response to market demand, Apple has implemented further management with Battery Health Management. Additionally, to get the full performance of your MacBook, it will utilize both power from the mains and the battery.