This is a very profound and insightful question which has been asked for generations. It is NOT directly and clearly addressed in Scripture and so we will present separately the following arguments for YES and then for WE DON’T KNOW positions.
First the rationale for, YES:
The age of awareness is when we have the ability to distinguish good from evil. In Deut1:39 ( Old Testament) the children were allowed to enter the Promised Land. The adults that had not trusted God did not get to enter. Young children have not rejected God’s revelation as they aren’t aware of it. Hence, one who has not rejected the Word of God will be saved. God who is merciful and loving can be trusted to do what is right, just and fair.
Jesus blessed ‘little children’. He even said, “Such is the Kingdom of Heaven.” He certainly would never bless someone going to Hell. The root question is, does God treat willful knowledgeable disobedient sin differently from our inherited sin nature from Adam?
Second the rational for, WE DON’T KNOW:
There is only ONE WAY TO HEAVEN …TRUST IN CHRIST. Jesus said, ”I Am the Way, the Truth and the Life. No one comes to the Father but through ME.” All [which would include children ] have sinned and come short of the Glory of God.
When a child reaches the age of accountability (i.e. the age of innocence is over, which varies for each one), then they are aware of their need for a savior. Children as young as 4 or 5 have been known to pray to invite Jesus into their lives and receive the assurance that they have heaven as their eternal destination.
In summary, we all like to believe and hope for the YES answer of course and that is most likely the case. However, we can absolutely trust a loving and merciful God to judge fairly the ‘little children’. That is what we should do also, trust God.