Controlling percentages can change, as can state restrictions on a number of conditions.
As I said it's not something I've dug into the details of.
The largest lithium mining company in the region is Sigma Lithium..
Tesla was negotiating to buy the Sigma Lithium but now the Chinese BYD is the favorite.. [0] [1]
China companies are currently owning the EV market in Brazil , and many other developing contries, and they have plans for both cars and batteries factories in Brazil, but they need access to lithium for that and so they are going for the lithium mining companies as well..
Musk not only need the lithium but he also want to block the grow of Chinese companies that are owning the market in many developing countries where Tesla is not present and are even growing fast in Europe..
Musk expect that a right wing government will align with him, and be in favor of blocking China and that would open the door for him to buy the mining companies instead..
[0] https://www.reuters.com/technology/tesla-considering-bid-sig...
[1] https://www.ft.com/content/3c55d69b-6932-4255-ad79-daeced372...
Things in Brazil are not simple as that. Bolsonaro, the latest right wing president, did more business with china and russia than expected. He was one of the first chief of state to fly to Moscou when Russia invade Ukraine, to reinsure brazil would be neutral on this war. (same position of Lula).