HFs stakes in public companies through derivatives

I sometimes see that HFs initiate positions in companies through derivatives.

- What kind of derivatives do they usually use? Swaps, etc.

- What derivatives give you voting rights in the underlying?

- What are the reasons behind entering a name through derivatives?

As an example, last year TCI was shareholder of Cellnex (CLNX SM) and on top of that had a stake through derivatives that later converted into shares. Was wondering whether it's just a way to optimise for any price impact of buying shares on the market or there is more to it (leveraged position through swaps, etc.).