User Manual Samsung QA65Q70AAW 65" Q70A QLED 4K Smart TV

Thank you for this product question, this will depend on how you wish to view your TV, there are a few different options, Flat against the wall, Full Motion, Tilt option. I'll attach a web link to all models for you to view that will take a 65" TV for example you will see models that see suitable for 40 to 65", 40 to 100" any model that does not cover 65" to avoid.

Press the House icon Home button on your remote control to bring up the Smart Hub and then select Gear cog Settings.
Scroll down to the General tab and select Voice.
A pop-up box will appear asking if you would like to set up Voice Assistant. Select OK to advance.
Select Amazon Alexa to begin the setup process.
You will be asked to sign in with Amazon. You can do this by either going to the provided URL and enter the authorisation code, or you can scan the QR code where you will be taken to the Amazon page to sign in to your account.
Select Enable.
The Alexa setup is now complete. Select next.
Now you can try speaking to Alexa.
You can hold the Microphone button on your TV remote to speak to Alexa