No, 2 or more runners with a force play in effect and less than 2 outs. Meaning bases could be loaded. Not in effect with 2 outs, runner only on first, or anytime there’s not a force play in effect.
The rule applies only when there are fewer than two outs, and there is a
force play at third base (i.e., when there are runners at first and second base, or the
bases are loaded).
[1] In these situations, if a
fair fly ball is in play, and in the umpire's judgment is catchable by an infielder with ordinary effort, the umpire shall call "infield fly" (or more often, "infield fly, batter's out" or "infield fly if fair" when there is a chance of the ball drifting foul). When the rule is in effect, the batter will be out
[2] regardless of whether the ball is actually
caught.
Umpires typically raise the right arm straight up, index finger pointing up and call to signal the rule is in effect.
If "infield fly" is called and the fly ball is caught, it is treated exactly as an ordinary caught fly ball; the batter is out, there is no force, and the runners must
tag up. On the other hand, if "infield fly" is called and the ball lands fair without being caught, the batter is still out, thus there is
still no force, and the runners now
have a choice to tag up or to run, as opposed to having to run when the batter is not called out due to this rule (because the ball was not caught). This rules frees the runner from having to guess what the infielder, who may or may not catch the ball, will ultimately do. In either case, the ball is
live, and the runners may advance on the play, at their own risk.
An infield fly may be declared by any umpire on the field.