Hardware flow control support for the request to send (RTS) and clear to send (CTS) signals.
The corresponding pins should be configured by pin mux as LPUART RTS/CTS.
The alternatives for each pin you can find in the pinout in the S32K144_IO_Signal _Description_Input_Multiplexing.xlsx
For the configuration of RTS or CTS look at the chapter 184.108.40.206 LPUART Modem IrDA Register (MODIR)
Related chapter 220.127.116.11 Hardware flow control
I hope it helps you.