Southwest Airlines has yet again made changes to its onboard policies. This time, the discount airline has partially rolled back a controversial requirement it introduced earlier this year for plus-sized passengers, which required them to book an adjacent seat in advance if they could not fit between a single seat’s armrests. Here’s what you need to know. Southwest will no longer force plus-sized passengers to buy an extra seat Last year, Southwest Airlines announced a new controversial policy affecting its plus-sized passengers . Beginning this past January, any plus-sized passenger who did not fit between the armrests of a single seat would be required to pay in advance for an extra adjacent seat. If the passenger did not, they would be required to purchase an extra seat at boarding. If no extra seat was available, the passenger would be denied boarding and would need to buy an additional seat on the next available flight.…