Your computer won't explode; if it gets too hot, you'll start to see degraded performance and more frequent crashes and spontaneous reboots well before the CPU goes into the 'red zone', and you'd have to deliberately overheat your CPU to an out-of-spec high temperature to cause lasting damage.
That said, according to the information I can find, 85 - 90°C is a little hot for that processor; the average operating temperature for an Intel Core i7 is around 50°C – 66°C, according to manufacturer specs. You may want to check the heat sink for dust and make sure the fan isn't obstructed.
As for your CPU usage, there isn't really a 'typical' example (it all depends on what the computer is doing at the time), but 70% or higher isn't unheard of when it comes to gaming (as a point of comparison, my CPU usage is bouncing between 30-60% with Steam and Brave running concurrently). If it's sitting idle and consistently hits 80%, though, you'll probably want to take a closer look.