In my view OT saints went immediately to Heaven when they died, just like believers do today......The righteous who died before the coming of Christ are now in God’s presence. As to whether they were in heaven before He came, or in some other place of blessing, the Bible does not ‘clearly’ say.
I do believe that everyone is saved through Christ. He died for the sins of the world. For OT Saints it was future. For us, it is past, but it is still through Christ. It was His death, His sacrifice. It atoned for the sins of the OT saints as well as the NT saints.
I realize also that people differ on how they see the saints of the OT after death.....we’ve seen presented that in Ephesians 4:8 when it says,... “When he ascended on high he led a host of captives, and he gave gifts to men”?....So I realize some have taken this “host of captives” to refer to the OT saints who have finally been released from their state of limbo and allowed to enter Paradise.
But I tend to lean to the idea that it was satan and his demonic angels who had just been defeated through Christ’s death and resurrection, and ‘who were then’, though figuratively, led in chains as Christ’s captives in His triumphal victory march into heaven.... They are being flaunted as the spoils of victory..........that Jesus proclaimed his triumphant victory over his enemies, even before the resurrection takes place.... He was announcing the truth of Colossians 2:15 where it states.... “And having disarmed the powers and authorities, he made a public spectacle of them, triumphing over them by the cross.”
I actually like that better than any other explanation I've heard.