@Neil300there's no way to completely disable all peek notifications as far as I know. you might want to try enabling Do Not Disturb (DND) mode, just make sure to go to Settings > Sound > Notifications > Do not disturb > Block visual disturbances > enable Block when screen is on. that way, when you enable DND mode, the notification banners won't be showing up.
there's a way to change priority of some notifications, but it's a more convoluted process and you can't do that for all apps at once, just one by one. first, you need to pull down the notification panel, and long press the cogwheel icon until it starts spinning and you feel a slight vibration. this enables you access to System UI Tuner, which can be found at the very bottom of the Settings menu. in Settings > System UI Tuner > Other > you can enable Power notification controls. once enabled, you can go to Settings > Apps, tap the app you want to disable notifications from, open Notifications, tap the turquoise A icon so that it fades to gray, and then slide the Importance slider left or right. setting the slider to the 4th dot from the left (titled "No full screen interruption or peeking") should disable any notification banners from that app.
