> For example, right now my laptop is at 63% battery and currently charging. It’s drawing 36W at the moment. When the battery charge is lower, it’s drawing more power from the outlet, and the higher the battery charge is getting, the less power it’s drawing from the outlet.

This is because Li-Ion charging logic is known as "CC-CV", or constant current followed by constant voltage. You limit the charging current to some value (say 1A) until the cell attains the target voltage (almost always 4.2V, though some chargers limit it to 4.1V to prolong cell life), and then you hold it at that voltage until the current diminishes significantly (most chargers cut the cell off and indicate charge complete when the current draw drops to 10% of its max (during the CC phase) charge current, i.e. 100mA here).