No, cannibalism is not being commanded. It is being predicted.
The Hebrew word translated as "you shall eat" in this passage is the word "וַאֲכַלְתֶּ֖ם " (wa·’ă·ḵal·tem). This verb is of the weqatal form, and, like yiqtol verbs, ordinarily connotes simple future tense in Hebrew.
In the Ten Commandments, most of the commandments are given in the negative, and Hebrew has some special rules for this which change the verb form after the "not" in Hebrew. But an example of a positive command is given in "Honor your father and your mother." The word "honor" is the piel form of the verb, and carries the imperative sense.
So in the Levitical passage of the question, the verb is not given in the command form. It is simply a future tense, informing the people of what would occur in consequence of their actions.
EDIT: The real answer here is derived from looking at more of the context. The same weqatal verb forms are used in this passage beginning with verse 25, but they occur in the passive voice construction. In Hebrew it is impossible for a command (imperative) to exist in the passive voice. Therefore, it is understood that, instead of being a command, which the passive-voice context does not allow, or perhaps even the simple future sense of meaning, this is a curse. Curses reference the future, but are not commands; rather, they predict woes to come.