XFL games will be broadcast on FOX, ESPN and ABC in the United States. Elsewhere, like in the UK for example, BT Sport will cover the league weekly; for reference, BT currently carry WWE's core programming like Raw, SmackDown and NXT, so there's already a subscriber base accustomed to the channel's format.
Is the WWE Network part of all this? No, not yet.
Subscribers to WWE's in-house on-demand service won't have access to XFL games in the short term, and plans haven't been announced for the long term either. There's a chance that the league could become a tiered extra if WWE ever get round to offering those to customers, but that's probably a long way off.
For now, the XFL is strictly set for standard television, not the Network. One slight surprise is that WWE didn't offer up the old content (they still own the rights to the 2001 season's games) as a precursor to the 2020 launch.