From what I can tell, there is no right single answer to how the relationship between a warlock and their patron works, and there is considerable flexibility for a player to define this themself (along with their DM if playing tabletop). I’m not sure if anyone has already quoted the relevant section from the standard class description, but I’ll put here as I can’t see it:
A warlock is defined by a pact with an otherworldly being. Sometimes the relationship between warlock and patron is like that of a cleric and a deity, though the beings that serve as patrons for warlocks are not gods. A warlock might lead a cult dedicated to a demon prince, an archdevil, or an utterly alien entity—beings not typically served by clerics. More often, though, the arrangement is similar to that between a master and an apprentice. The warlock learns and grows in power, at the cost of occasional services performed on the patron’s behalf.
The magic bestowed on a warlock ranges from minor but lasting alterations to the warlock’s being (such as the ability to see in darkness or to read any language) to access to powerful spells.
Also possibly relevant here is
this tweet from Jeremy Crawford of WotC, implying that once a warlock has learned powers from their patron they’ll keep them no matter what happens to their relationship. Though this seems to make more sense in the context of a master/pupil type relationship than a deity/disciple one.
