Smaller reverbs or short delays make things sound bigger. Reverbs with decays under a second and delays under 100 milliseconds usually make a track sound bigger instead of pushing it back in the mix, especially if the reverb or delay is in stereo.
Long delays, long reverb pre-delays and reverb decay settings will make things sound further away in the mix if the level of the effect is loud enough. Delays and pre-delays over 100 milliseconds will be distinctly heard as they begin to push the sound away from the listener. The trick between something sounding big or just distant is the level you have the effect on the buss channel. When the decay or delay is short and the level is loud, the track sounds big. When the decay or delay is long and loud, the track just sounds far away.