No event has a necessary effect : after any event, X, the universe might vanish into nothingness, and so X would have no effect. In other words, no event, Y, is 'doomed' to follow another, X, as its effect.
However, once you describe X as a cause, then of course it must have an effect. Cause and effect are correlative notions.
Can the effect 'be considered part of the cause' ? No, because cause and effect need to be independent events or sets of events. Unless they are distinct, either logically or empirically, you lose the plurality inherent in causation. One event causes another event as its effect; if the effect were part of the cause we would not have two events, but one.
Even if we take Davidson's point that 'The cause of B caused B', which describes B and its cause in a way that logically connects them, this still assumes that B and its cause are distinct events and in this sense independent. I take 'independent' to imply 'separately specified or specifiable'. 'The rising heat of the gas (X) caused the boiling of the kettle (Y)'. 'The rising heat of the gas' (X) makes no reference to (is specified separately from) 'the boiling of the kettle' (Y); and 'the boiling of the kettle' (Y) makes no reference to (is specified separately from) 'the rising heat of the gas'. Yet X caused Y.
The notion of the independence of cause and effect derives from Hume's account (A Treatise of Human Nature, 1739-40) of all events (he calls them 'objects') as 'perfectly distinct' : https://people.rit.edu/wlrgsh/HumeTreatise.pdf. It was popularised by A.I. Melden in Free Action.
Donald Davidson, 'Actions, Reasons, and Causes' in The Joulrnal of Philosophy LX, No. 23 (1963), 696. Reprinted in Essays on Actions and Events, ISBN 10: 0198246374 / ISBN 13: 9780198246374
Published by Oxford University Press, USA, 1980.
David Hume, A Treatise of Human Nature, 1739-40): https://people.rit.edu/wlrgsh/HumeTreatise.pdf.
A. I. Melden, Free Action, London, 1961, pp. 52-53