A few weeks after buying Neymar, PSG also secured a loan deal for Mbappé — then the rising star of French soccer playing for Monaco — that included the option to make the move permanent in 2018.

One of the most electrifying transfer stories of the modern era is taking shape. Florian Wirtz to Liverpool isn’t just a signing—it’s a statement. In a world driven by ambition and eye-watering sums, ...