The Sky in the City or Suburbs without instruments is pretty sparse, except for the moon.
From a dark sky the is wondrous (Observing from Dark Skies), even without any instruments. The Milky Way is gorgeous. Start clusters become more numerous and more bold. You can see the Andromeda Nebula and some Globular Clusters with the naked eye (depending on your location and the date).
Add in binoculars or a telescope and the sky opens up.
Location, Location, Location!
Your Location makes the Biggest Difference in what you can see.
Your targets are fewer in bright skies. Bright objects, like Jupiter, Saturn, and star clusters are readily observed in the city. "Faint Fuzzies" like galaxies and nebulae may be invisible regardless of the size of the equipment you have. Just like in the daylight, the stuff is there, it's just completely washed out.
The brightness of the sky will determine how dim an object is possible to see from a site.
As your sky gets darker, the more valuable your equipment gets. You can have an amazing night with a $100 4-inch refractor if the sky is dark enough.
Size Matters!
The diameter of your telescope's mirror or objective lens will determine how dim an object can be visible to your eye. The bigger the telescope the more you'll be able to see.
The diameter of your telescope will set a limit of how much magnification it can support. A rule of thumb is 50x per inch (or 2x per mm). it's quality (and glass types) will set an upper limit on the percentage of that maximum value it can reach.
Its focal length will set a limit on how wide a field of view you can achieve.
Your telescopes widest field of view and it's highest magnification will make some objects better targets than others.
One of my favorite scopes was an inexpensive 4-inch achromatic refractor. Its short focal length allow very wide views. It was a perfect scope for browsing through the Milky Way in a dark sky. I was able to see the Pinwheel Galaxy for the first time with it, after failing with bigger scopes from brighter sites. But it was very bad at high powers on Jupiter and Saturn. 40x was about the maximum magnification for it on Jupiter. That's sufficient to see the Galilean Moons, but not to see surface detail. They're still great scopes, but not versatile.
An 8-inch reflector IS very versatile, supporting much higher magnifications while still supporting relatively wide fields at low power.
Your targets are limited by your sky and your scope.