JSN-SR04T-2.0 comes with a built in LED which turns on when the sensor is used for the first time after restart.
i only need to take measurements every 5 minutes so is there a way to put this sensor into sleep mode and turn this led off when not in use to conserve power?
I don't know about being able to put the sensor in sleep mode, but certainly you can cut the power to it using a transistor. Even if you do that, I would still desolder that LED though.
Also, since the "working current" of the "-2.0" version is reportedly low (8mA per some datasheets) you could also try powering it with an Arduino pin; i.e., no transistor required to turn it on and off. Shouldn't do that with the "original" version, since it requires higher current (30mA per some datasheets).