Why? There seems to be a pattern in this forum to give everyone but China the initiative. India can decide the scope and tempo of conflict, America can decide the scope and tempo of conflict, but heaven forbid China do anything but fight with one hand tied behind its back. If China decides there's going to be war, it will be to destroy India and cripple any capacity it has to threaten China for a hundred years.
I think China will hold back, or at least do all it can to disguise any use of cyber weapons.
Not because it is worried about things ‘getting out of hand’, but rather because those capabilities are intended for use against the Americans, and China does not want to tip it’s hand by revealing its true, full capabilities in those fields, which are unnecessary overkill against India.
Also, I think you are missing the point in China preferring to fight in the limited region America/India might choose attack.
That is a position born of strength, not weakness. You only need to look to expand the scope of the conflict if you are loosing the stand-up fight and need to hit your opponent where they are weaker.
In Asia, China has no weak spots an enemy might choose to focus on. Wherever an enemy might choose to fight, China has the raw power to take them head-on and not fear of being at a disadvantage.
If China is holding its own and even winning the stand-up fight in the limited region an enemy has attacked, why risk uncontrolled escalation by opening up new fronts elsewhere?
Remember, China is primarily focused on defending itself and driving off the attacker, it doesn’t need to then chase after the defeated enemy to take the fight to them unless it chooses to press home it’s advantage.
But tbh, if China can beat back a full USN assault on even footing, it doesn’t really need to worry about US bases in SK or Japan.
Those bases are untenable without US naval support, and at that stage, China could probably get them closed through diplomatic threats alone.