In my opinion, if there is a Taiwan conflict, India might attempt to invade the disputed territories with China and more. Both the Indian and Western media will be playing the: "China is losing badly. China is falling." propaganda on steroids. The Indian leadership, might feel supremely confident again, just like during the early Covid days, to backstab China again.
Just like Russia today, China should expect the US to rally a good number of countries to condemn, sanction, boycott, and sabotage it. In that crowd of hate, will be countries from both the developed, and developing world. India will obviously be on the top of that list, for it'll perceive this as its best opportunity to bring China down. Having India backstab China during a Taiwan conflict should be a dream come true for the Americans. So I'm sure that the US will try to encourage India to do just that. I could be all wrong, and India might actually just not take the American and JH bait. But it is better for China to prepare for an Indian backstab than to be caught by surprise. That preparation alone might actually deter India from pulling off any backstab altogether.
Indeed the Indian leadership appears to be leaning more to the West recently. But I think its not that simple. We should remember that India has no true loyalty other than to itself. For decades, India had been shifting its favour back and forth between the West and Russia. Usually depending on who is supporting Pakistan or China. As of now, I see some shift happening among some Indian elites towards the West. But they are still a relative minority. I guess the big shift can only come when Russia is perceived to take China's side in a hot Sino-Indo conflict. Most Indians in my opinion, think that India that is the center of attention between Russia and the West, and not India having to follow in either camps. In their minds, India has the enviable position of having good relationships with both the West and Russia, because of India's supreme importance in the world. India can curry favours from both, while China and Pakistan can't. I have my own opinions on this kind of Indian world-view, but neutrals and pro-Indians would argue that it is pragmatic.
I have always been expecting that sooner or later, India would outright backstab Russia and get real cozy with the West thanks to US pursuasion and Delhi's view that Moscow and Beijing are getting closer ever than before (and that Russia would become China's vassal thanks to the war in Ukraine).
Therefore, China should do its best to bring Russia completely over to its side and have Russia provide assistance to China in terms of intelligence on the Indian military, considering that at present, there are still significant amount of arms caches in India that are sourced from Russia. However, the later might not be very useful, but it would have to do.
Besides, as I have previously mentioned in the PLA Strategy for Taiwan Conflict thread - China must always be prepared for a two-front war
- One in the WestPac frontier over Taiwan and the SCS against the US and their "allies", and another one in the Himalayan frontier over Aksai Chin and Aruchal Pradesh against US-backed India.
Of course, the higher priority should be given to the WestPac frontier compared to the Himalayan frontier, since the WestPac is where the key for the ultimate survival of the Chinese civilization state lies (remember that the barbaric invasion of China by Imperial Japan started there). However, whenever possible, the WTC should be able to at least hold off the Indian invasion of Tibet on their own while waiting for the WestPac frontier to be dealt with. The goal is to make the Himalayan frontier into as much of a WW1-style static front as possible. This could last for years, but it should be managable for the PLA thanks to the terrain.
At the same time, the MSS and PAP should monitor Tibet closely for any signs of insurrection movements supported by India, aiming to destabilize Tibet and negatively affect PLA movements in the region. On the flipside, China should massively increase the support of separatist movements in northeastern India for the similar goals of making things difficult for the Indian military in the Sikkim and South Tibet region.
Meanwhile, India-Myanmar relations should also be watched closely by Beijing. If Naypyidaw shows any sign of openly supporting India's actions against China, China should reciprocate in kind WRT the separatist movements in northern Myanmar. In contrary to many's opinion here, I don't think China should rely on any meaningful help from Myanmar.
Plus, China should consider roping Pakistan in to help China and split India's attention. For this, I believe Pakistan doesn't need to invade India - Just massing troops along the Indo-Pakistan border and the Jammu & Kashmir (J&K) region would be helpful to keep some portions of the Indian military attached to the Indo-Pakistani border and the J&K region. However, I wouldn't count on Karachi heavily for their capability in helping China to hold India off, considering that their military leadership has been throughoutly infiltrated by pro-US elements.