No, Christians will not “find” grace after that declaration; they were, are, and will forever be the beneficiaries of grace already bestowed, now brought to its final, irreversible consummation in glory.
Revelation 22:11 is not describing an ongoing economy of redemptive grace after Christ’s declaration. These are prophetic indicatives announcing the arrival of final judgment and the irreversible confirmation of moral-spiritual state. The point is not that new grace will be found, but that the destinies already determined in Christ (for the elect) and in Adam (for the reprobate) are now fixed and manifested. The time for conversion, forgiveness, and covenantal transition has ended.