There are several settings for controlling and configuring you Ark: Survival Evolved Dedicated Server. If i do it manually, i risk really messing up the ini file.
but the option of these servers is just yes or no on single player experience, which i think automatically adjusts bosses to the 67% less difficulty. And don't forget, most of these settings apply just the same to Single Player & Non-Dedicated Sessions on Windows, Linux, and Mac! For detailed information on finding the customization files for these situations, or for a general overview of what customization can do for you, please see this page: Balancing Ark For Your Play Style.