Google Assistant is integrated into WebOS 5.0, which is installed on this OLED TV. The functions usually require a microphone, which is built into the LG remote controls. For this, you usually have to press a button on the remote control and then speak the commands.
As far as I know the 48'' model is newer and production is more expensive (has something to do with bad production yields). Also the 48'' model is pretty popular as a computer moitor so there's a larger market and since it's popular they don't lower the price. Even though it's pretty stupid that the larger model is cheaper than the smaller one.
If it's the same as the LG C9, you can. It also runs on webOS, so it should be the same.
You can find it under Options - Picture - Energy Saving - Screen Off.
Due to different suppliers and delivery conditions, there may be price differences compared to other suppliers. We always try to set a price in line with the market, but this is not possible for all products.
I was also surprised, but the substrate will indeed probably only be more complex to produce. Bringing the 4k to 48" is trickier than to 55", because the density is higher. In our case, the space problem was decisive for the 48". The picture, by the way, is splendid and bright enough, even during the day when the sun is shining.
A certain way of dealing with OLED displays should actually be learned and applied, because burn-in can basically be avoided.
Enclosed is a suitable article from Digitec: https://www.digitec.ch/de/page/oled-und-burn-in-so-stehts-wirklich-um-ausgebrannte-pixel-8105
Quote from Luca in the comments on the question "Is burn-in on mobile phones covered by the warranty?
Important question! For most manufacturers (TV and mobile phones), burn-in is not covered by the warranty. Because burn-in only occurs when the device is used excessively in a way that was not intended. It's as if you were to continuously bang your new football against a concrete wall from a distance of two metres, until after five hours you go back to the seller and complain that the ball has broken.
BUT - manufacturers are very accommodating and repair or replace damaged panels free of charge or very cheaply. Especially in the TV sector. Unfortunately, I know less about smartphones.
I think this has to do with the fact that producing a 48" panel is more expensive than the standard 55". With OLED, it seems more difficult to make small TV panels than large ones, based on the non-existence of small panels (e.g. 27") etc.