Self-determination is not the same thing as freedom. The Islamic State, Boko Haram, and the Taliban are fighting for self-determination as described by the U.S. Declaration of Independence and the UN policy. Similarly, the South fought for self-determination, but for the sake of preserving slavery and its associated abuses. There are often "seperatists" in most large democratic countries who imagine carving out a fiefdom, usually with themselves conveniently in charge, involving prohibitions on cultural practices that differ from what would be the official line. This is often called freedom, in an Orwellian way. Most efforts to achieve self-determination are actually power grabs. Others involve people working together to preserve or expand their freedom and prosperity, such as the revolutions against autocrats that produced many of today's democracies, including the U.S.
So I don't think an informed person could answer yes or no to the question. It depends on the values of the people seeking self-determination. I'm for self-determination in the context of the U.S. Revolutionary War but against it in the context of Boko Haram. Sri Lanka's Tamil ethnicity? Unsure. The Kurds? I'm sympathetic. Some warlord in the Congo? Probably just a power grab.