I have 3 sensors then each sensor has TTL UART TX and RX
so is it possible to connect all RX pf sensors together and for TX of sensor an connect to Arduino Uno on three different pins
so I mean 3 RX of sensors connect to one TX output on arduino uno and for TX of sensors connect to other 3 RX on arduino uno
The TX of an Arduino can go to an arbitrary number of RX pins, but only one device should be wired to the RX pin of the Arduino - you need multiple serial ports for that