Combat in Winds of Viridia is built around the creatures of Viridia and the state they have been driven into. The valley's wildlife is frenzied, and the game's boss encounters escalate from that baseline into something considerably larger.
The standard enemies are animals and beasts in a berserk state, and they are the game's most common source of damage. Combat against them is where the movement system pays off directly - the roll and slide are as much a defensive tool as an offensive one, and a player who has learned the movement kit fights these encounters quite differently from one who has not.
Above the frenzied wildlife sit the giant bosses: enormous beasts, living statues and guardians. Preview coverage consistently draws the comparison to Monster Hunter-scale encounters, which is about size and escalation rather than about the multiplayer structure - this is a solo fight that is meant to be long and demanding.
The recurring adjective in the coverage is "seamless", and it applies to the fights as much as the traversal. There is no separate boss arena loading screen, so the build of your totem is what you walk into the fight with.
Three things determine your readiness, and all three are worth attention. First, the totem loadout - because totem choice changes your options in the fight rather than just your numbers. Second, your relic collection, since some totems need combinations you may not have assembled yet. Third, your movement practice, because the boss arenas are large enough that positioning is a real part of the fight.
The demo is the place to test the first and third of these. Even without the full relic set, running a boss with a totem you have tuned is a better use of demo time than exploring further, because the demo's fragment of the valley includes at least one encounter worth learning.