is it possible to use regular TVs along with plex to show floor plans and image films on screens? Power and network connection is given. However, somehow a schedule is needed to put TVs on and off (TV feature of course) but also to start plex and the right media. Would a consumer synology be good enough to cast to 4/5 screens in 720 or 1080p (different films)?
Review Plex’s TOS. Pretty sure it limits things to personal use only.
You’re probably better served by a digital signage system. Especially if you need to control display on/off times, schedule media start/stop times, insert ads/scrolls (like stock tickers, weather), etc.
As much as I’d love people using Plex over something else - I think in this case Plex is not for you.
I think for such applications you should look into ‘digital signage’ software. There is at least one open source project which can run on a Raspberry Pi or similar.