No telescope comes with all the accessories you need out of the box. Consider this list of accessories that many amateur astronomers buy over time. The exact accessory may depend on the telescope you buy.
What not to Buy
Generally you’ll get a 10mm and a 25mm plossl eyepiece that fits a 1.25″ focuser. Stick with those. They’re all you’re going to need for a while.
Avoid buying color filters as they are virtually useless.
Also avoid buying any 1.5x, 2x, or 3x (any) barlow lens. They’re not very useful.
Do Consider Buying
A collimation tool.
45 or 90 degree angled view finder.
Cold weather clothing e.g. Artic coveralls rated to -32F.
An observing chair and table (nothing specific).
A flashlight or head light that emits red light.
Carrying case or backpack for your scope. Note: keep the foam inserts that come with your scope you may use them in the carrying case.
A decent set of beginning star maps. We like the Pocket Sky Atlas from Sky and Telescope.
A decent pair of binoculars. The Bushnel Powerview 10×50’s Porro Prism Binoculars are good.