MKR 1010 and Nextion

I have used MKR 1010 board with Nextion display, using the Nextion library.
I was able to send messages to Nextion to show that the MKR 1010 is trying to connect to a local wifi, that unfortunately never connects.
Anyway, what I would like to know is if it is safe to connect to a Nextion device that works on 5 V, being the MKR 1010 a board that works on 3,3 V.
When the Nextion Tx sends something to the Arduino MKR 1010 Rx, is it using a 5V signal?, if yes, what can happen to the wifi board?
Can I use other sensors as, for example, DHT11 temperature and humidity sensor, that work at 5V with the MKR 1010 board?