It really looks that way. In chapter 14 of the Westminster Confession of Faith we read that

the principal acts of saving faith are accepting, receiving, and resting upon Christ alone for justification, sanctification, and eternal life, by virtue of the covenant of grace.

So we rest upon “Christ alone” not only for justification but also for sanctification.

I have to admit I feel like I’m missing part of the story that might help explain why the Divines used this precise formulation. I don’t doubt that sanctification is God’s sovereign gift, and is given monergistically. But I find it hard to put the precise expression together with how we are supposed to work out our sanctification. Subjectively speaking, I often here statements from Reformed exegetes that indicate that a person’s means of pursuing justification and pursuing sanctification are different.

Q. 77. Wherein do justification and sanctification differ?
A. Although sanctification be inseparably joined with justification, yet they differ, in that God in justification imputeth the righteousness of Christ; in sanctification his Spirit infuseth grace, and enableth to the exercise thereof; in the former, sin is pardoned; in the other, it is subdued: the one doth equally free all believers from the revenging wrath of God, and that perfectly in this life, that they never fall into condemnation; the other is neither equal in all, nor in this life perfect in any, but growing up to perfection.