It's possible for "I request immediate X" to be either a polite request or a polite demand.
Let's first clarify and say that a "request" is asking for something that you might be refused, and "demanding" is asking for something that you cannot be refused.
There's pretty much no polite way to use the verb "demand" when demanding something, no matter who you are or who you're demanding from. One natural way to politely demand something in English is to use the verb "request". The context alone indicates whether it's a request or a demand.
From a customer in a restaurant, for instance, "I request to see the kitchen" is likely a request because a restaurant could easily refuse customers access to the kitchen. But if a health inspector says the same thing, it's clearly a demand because health inspectors have to be given access to the kitchen.
Using the verb "request" is just a formal way of saying "Could you..." or "I'd like to..." etc.. With those forms of request, if they come from your boss, they're polite demands, not requests.