Almost all vocals (these days) include some delay. Most good delay plugins will include presets specifically labeled for vocals. That is a place to start.

Don't forget, the Rotary Speaker thing was a guess on my part. When you try it, pay attention to the amount on the "mix dial" (or "wet/dry" if it has that). turn that down at first to keep the effect "subtle". (Same with delay) then try higher settings to see how they affect thee vocal - and most importantly, how it sits in the mix.

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