Wirtz, a Germany international, is set to undergo a medical with Liverpool later this week.
He has been on holiday since his national team commitments ended last week, and has spent time with former teammate Jeremie Frimpong, who will also be joining Liverpool.
According to reports, Liverpool are initially paying £116 million for Wirtz, but the total amount could increase if all bonuses are fulfilled.
Under this scenario, Bayer Leverkusen, Wirtz's current club, could receive a total of £124.6 million from the sale.
