Preconditioning before asking a favor Suppose I want to borrow an item, such as a phone charger from someone.

Instead of directly asking them, "Could I borrow a charger?"

I first ask this question: "Do you have a charger?"

The act of asking a question of fact (whether they have the item or not) will make them more willing to lend you the item.

Is there a term or explanation for this? 

Is this related or similar to the Ben Franklin effect and Anchoring effect?
The effect you ask about could very well be seen as an example of the Ben Franklin effect, also known as the foot-in-the-door phenomenon.
In your example, replying to the question "Do you have a charger?" would be interpreted as a small favor which is then followed by the bigger favor of lending the item.

Reference:

Beaman, A. L., Cole, C. M., Preston, M., Klentz, B., &amp; Steblay, N. M. (1983). Fifteen Years of Foot-in-the Door Research. Personality and Social Psychology Bulletin, 9(2), 181-196.DOI: 10.1177/0146167283092002