*Setup:*
I've connected a power bank to the camera's USB-C port for continuous power.

To enhance cooling, I've flipped out the monitor.

To minimize power usage by the monitor, I covered the sensor next to the viewfinder with a black nail clipper.
This trick allows recording to continue while the monitor is turned off.
I also set the [Auto Power OFF Temp.] to [High].

I'm using a SanDisk 512GB Extreme microSDXC UHS-I Memory Card, which supports up to 190MB/s. It's the best card I can afford, which means I haven't tested some high-end recording formats like XAVC HS and XAVC S-I. I've only tested the more common XAVC S format.

*Test Results:*

*4K 60fps 10-bit [200 Mb/s]:*
Record stopped at 18:40 due to overheating.
Frame dimensions: 3840 x 2160
Data rate: 200,021 kbps; Total bitrate: 201,557 kbps
Frame rate: 59.94 fps

*4K 60fps 8-bit [150 Mb/s]:*
Record stopped at 26:05 due to overheating.
Frame dimensions: 3840 x 2160
Data rate: 150,012 kbps; Total bitrate: 151,548 kbps
Frame rate: 59.94 fps

*4K 30fps 8-bit [60 Mb/s]:*
Record stopped at 59:37 due to overheating.
Frame dimensions: 3840 x 2160
Data rate: 56,989 kbps; Total bitrate: 58,525 kbps
Frame rate: 29.97 fps

*HD 30fps 8-bit [50 Mb/s]:*
Recording continued past 10:25:15.
Frame dimensions: 1920 x 1080
Data rate: 49,588 kbps; Total bitrate: 51,124 kbps
Frame rate: 29.97 fps

The A6700 surpassed the ZV-E10, which lasted 6 hours; the A6700 reached up to 10 hours of recording time in HD.

However, if you're aiming to record in 4K resolution for extended periods, you might still need to add a cooling device behind the camera.

If your goal is to achieve prolonged 4K recording, consider using an alternative like the iPhone 13 Pro.