In the video I'm using the Terra Curio mod alongside the Curios compat layer.
But I have also tested this with the Craftable Capes mod alongside the Trinkets compat layer, and in both cases, other players in multiplayer scenarios could not see the equipped accessory's model in game.
In multiplayer, when a player equips an accessory with a visual 3D model on them, other players can't see it.
Video demonstration: https://streamable.com/t9uzl9
In the video I'm using the Terra Curio mod alongside the Curios compat layer. But I have also tested this with the Craftable Capes mod alongside the Trinkets compat layer, and in both cases, other players in multiplayer scenarios could not see the equipped accessory's model in game.
Forge Version: 47.3.3 Minecraft Version: 1.20.1
Accessory mods used: _accessories-1.0.0-alpha.24+1.20-neoforge accessories_cclayer-7.4.0-alpha.13+1.20 accessoriestclayer-3.8.1-alpha.12+1.20