Is there a standard target level for spoken audio in a tutorial video? I record a lot of tutorial videos for my work. I don't use background music or sound effects, just a voice over a screen recording.

One thing I have noticed is each of my videos (so far) has a different overall volume. If people were to listen to the videos in succession, they would be constantly adjusting the volume level. I want to normalize the audio so that it is all at the same level.

My problem is I can't seem to find a standard anywhere for a general decibel level to normalize all my videos to. Is there an ideal audio level that plays at exactly the level a typical viewer would expect for their volume setting?

In other words, if a viewer was just watching, say, a professionally made movie, and then watched my video, ideally they should not have to adjust the audio setting on their computer when switching to my video.
There's no single answer - it's a series of trade-offs:

When you record your voice, it should be as loud as possible, but making sure never to go over the maximum level that can be recorded.  This is known as clipping, and sounds distorted.  Too quiet, and your audio will be hissy relative to the noise floor of your setup - too loud and it will clip.

In order to smooth out the overall levels, you can dynamically compress your audio (this is not the same as data compression), either before it is recorded (between the mic and recorder) or after it has been recorded.  This is effectively like having an automatic volume control, where levels over a certain threshold are turned down, so that the overall effect is smoother.  Too much compression can sound pumping and aggressive - like an FM talk-radio host.