Not sure what you mean by one time constructor function, but you can pass the result of a function to initial value.
const { current: myStableValue } = useRef((() => { //called once })());
If you want to lazily initialize a ref, you need to manually check if it has been initialized and run your expensive code if it hasn’t. Dan Abramov provides what appears to be a pattern officially recommended by the React team: https://github.com/facebook/react/issues/14490#issuecomment-...
Edit: I guess it would be a bit inefficient to invoke the IIFE every render just to initialize the value once. Probably better to use useMemo with [] as the dependency list then, either one achieves the same result.