The soundstage can always only be as good as what’s on the recording, and a good setup should reveal huge differences between recordings. Lousy recording, lousy soundstage.
Phase coherency and time alignment of the drivers are significant contributors to good sound stage....kind of tough to make much progress if the speaker design isn’t up to snuff.
The room is a major part. Speaker position and listening position within the room are key areas to pay attention to. Every room is different, so experimentation is critical. You can follow good rule of thumb practices as a starting point, but use your ears to fine tune. Room treatment to address reflections, resonances, standing waves, and nodes, etc., can be done with carpet, drapes, and furniture, or aftermarket or DIY wall and ceiling treatments, and bass traps ... all can help tame the room. Its and art and science in itself.
Transparency of the system is also a significant factor...superb clarity reveals more of what’s on the recording. The whole system (speakers, amps, cables, crossovers, wires, connectors, preamps, phono stages, DACs, carts, TTs, tonearms, streamers, EQs, etc....everything in the path) has the potential to mask what’s available on the recording....all do to some degree. The difficult part is chasing down clarity in that entire path. Vibration damping and isolation of components is worth pursuing to optimize what you have. There’s no way around trial and error, and there will be many occasions of two steps forward, one step back (or vice-versa), but every step forward should reveal a bit more of what's on that recording. It’s a journey....enjoy!