It seems you are using Orin Nano rather than Jetson Nano.
I’ve moved your topic to correct category for Orin Nano.
You can refer to the following thread for the similar use case to invert RTS.
Need to Invert UART2 RTS - #11 by KevinFFF
For the UART1 from 40 pins expansion header, the register should be 0x03100020.
$ sudo busybox devmem 0x03100020 w 0x8
$ sudo busybox devmem 0x03100020