The datasheet says the control current is 7.5 mA at 12 V. It doesn't say what it would be at 3.3 V, so that would be the one thing I'd worry about. ESP8266 GPIO pins can source a maximum of 12 mA, so if you want to hook it up in a way that uses the GPIO pin as the current source there might be some issues.
I think to be safe, I'd just go ahead and add a transistor. That also can provide protection against a logical 1 being enough less than 3.3 V or a logical 0 being enough more than 0 V to cause problems.
You can find similar relays on Amazon for a bit less (search "solid state relay"), and even cheaper on AliExpress if you aren't in a hurry.
The datasheet says the control current is 7.5 mA at 12 V. It doesn't say what it would be at 3.3 V, so that would be the one thing I'd worry about. ESP8266 GPIO pins can source a maximum of 12 mA, so if you want to hook it up in a way that uses the GPIO pin as the current source there might be some issues.
I think to be safe, I'd just go ahead and add a transistor. That also can provide protection against a logical 1 being enough less than 3.3 V or a logical 0 being enough more than 0 V to cause problems.
You can find similar relays on Amazon for a bit less (search "solid state relay"), and even cheaper on AliExpress if you aren't in a hurry.