Leaving the hotspot will for sure. Bluetooth will as well, but not nearly as bad as the hotspot. Just my experience. I leave my Bluetooth on always due to me having an Apple Watch series 2. And it doesn’t seem to drain battery much at all. Now turning on my hotspot and leaving it on will kill the battery fast!! I would only use the hotspot as needed unless you keep your phone plugged in all day. JMHO.
In my experience, if I leave my Bluetooth on overnight.. My battery will deplete around 5% to 7%. Whereas if I off it, the battery will only deplete about 1% to 2%