Feral Contest

If you attack with the first targeted creature but the second targeted creature isn’t able to block it (for example, because the first targeted creature has flying and the second one doesn’t), the requirement to block does nothing. The second targeted creature is free to block whichever creature its controller chooses, or block no creatures at all.

Casting Feral Contest doesn’t force you to attack with the first targeted creature that turn. If that creature doesn’t attack, the second targeted creature is free to block whichever creature its controller chooses, or block no creatures at all.

Tapped creatures, creatures that can’t block as the result of an effect, creatures with unpaid costs to block (such as those from War Cadence), and creatures that aren’t controlled by the defending player are exempt from effects that would require them to block. Such creatures can be targeted by Feral Contest, but the requirement to block does nothing.