You can reorder user constraints within the associated constraint set. In the Sources window, drag and drop the XDC files to rearrange the order.
To get an ordered list of all XDC files that the Vivado IDE
processes, use the following command in the Tcl Console:
report_compile_order -constraints. This lists all the constraints in the
design, including user constraints and IP.
Note: For more information on how to change the order of constraints, see the Vivado Design Suite User Guide: Using Constraints (UG903).