@mdquitoras Great question! Here is an article by Sam Storms at the Gospel Coalition on this topic. I think he does a great job of summarizing the basic arguments. Regarding your specific question about Romans 3:23, I think his 4th point is is very relevant:
“There is the consistent testimony of Scripture that people are judged on the basis of sins committed voluntary and consciously in the body (see 2 Cor. 5:10; [1 Cor. 6:9–10]). In other words, eternal judgment is always based on conscious rejection of divine revelation (whether in creation, conscience, or Christ) and willful disobedience. Are infants capable of either? There is no explicit account in Scripture of any other judgment based on any other grounds. Thus, those dying in infancy are saved because they do not (indeed cannot) satisfy the conditions for divine judgment.”
Romans 3:23 would then apply to all who have had the ability to consciously reject truth, which requires a certain mental capacity. Babies do not have said mental capacity, therefore they would go to Heaven.
Another approach is to recognize that in Jesus we see the love and goodness of God. Because we know God is good, we can trust that His judgments will be just. We may not know exactly how God deals with every person who dies, but because of what we know of God through Jesus’ life and death and resurrection, we can trust in God to do what is right. Sam Storms seems to close with a similar sentiment about trusting God’s character.