Although you can click and drag cards to manually set an order in your lists, Placker also gives you the option of setting them automatically by dates.
This helps for example when you have a big to do list and want to focus on cards that will be due soon.
In this case, you can click the title of the list to be sorted, and in the panel at the right, select earliest values to appear first.
In the Gantt chart view, when cards are grouped by list, it's also possible to click the list title and sort cards.
There is also an option to click "Set order" by start and end date. This will reorder all cards in chronological order, regardless of their lists.
In the Gantt set order case, you will simply view cards in that order while you are in that view, while using the "sort cards in list" button will actually reorder and save changes in the order (including in Trello, in case it's a connected board).