Short answer
Halo: Campaign Evolved has campaign co-op multiplayer. Official pages list up to four-player online co-op with crossplay and cross-progression across PC, Xbox Series X|S and PlayStation 5. Console versions also support two-player split-screen. This site has not found an official competitive PvP multiplayer announcement for Halo: Campaign Evolved.
Multiplayer feature table
| Feature | Status | Notes |
|---|---|---|
| Online campaign co-op | Yes | Up to four players. |
| Crossplay co-op | Yes | PC, Xbox Series X|S and PS5 are listed. |
| Cross-progression | Yes | Official copy describes shared progression. |
| Console split-screen | Yes | Two-player split-screen on Xbox Series X|S and PS5. |
| Competitive PvP | Not announced here | Official pages emphasize campaign co-op, not PvP matchmaking. |
Why the wording matters
The title is called Campaign Evolved, and official materials focus on the rebuilt campaign, Operation: Meteorite, co-op and replay modifiers. If you are looking for classic arena PvP, wait for a direct official PvP announcement before buying for that reason.