Bore sighter is not needed. I take the bolt out of my gun and place the gun on benchrest an adjust so I can see a target centered though the bore of the gun. I then adjust the scope to be centered on the target. I usually do it at 50 yds.
Keep in mind that you still have to make final adjustment by shooting as bore sighting will only get you close.
Most of my hunting guns are zeroed at 200 yds. For most high-power rifles this will mean that the gun will shoot about 1 1/2 to 2 inches high at 100 yds and about the same low at 250 yds which is close enough for big game hunting so you don’t have to worry about hold over out to 250 yds.
One of the biggies is intended use. For example, if you have an AK or an AR carbine, then a red dot quick reaction type sight is ideal for ranges of 150 to 250 yards. If you have a .308 rifle that can reach out beyond 250 yards, then a good scope and rings is a the idea. Send me a PM.