Yes, you can turn monetization off, buy views, then turn it back on. Many views services will say they are monetization friendly and with such views you can leave it turned on. Some people do choose to turn monetization off when buying any views and engagement services regardless until they have been added to the video.
You can't get a YouTube channel banned or demonetized for fraudulent views and engagement. If fake views, likes, etc. are detected they are simply removed. If that happens, your video ranking may be negatively impacted but that's about the worst thing that can happen. Buying views and engagement is generally regarded as safe for YouTube channels.