..."These are the ones who come out of the Great Tribulation, and washed their robes and made them white in the blood of the Lamb."
There is NO salvation/redemption for ANYONE of ANY 'age' apart from the EXCLUSIVE 'Blood of the Lamb-Jesus'!
Salvation in every and all 'ages' is the SAME: Confidence in The Lamb's (Jesus the Lamb God has personally provided for redemption) death, burial, and Physical/material Resurrection according to THE HOLY SCRIPTURES, which ALONE can save believing sinners from eternal penalty/judgment of God's wrath! ( because of their being born sinners AND therefore active sinners.)
Trust the PROMISES of our LAMB-GOD, Jesus. HE/GOD is our Salvation. (The Penalty is PAID IN FULL, ONCE for all!)
Our God is Love! See 1st John 4:9-11.