[Question] How can you guys find out about these APIs

[Yukari-Tryhard]

I'm just a newbie and i want to learn how to capture these information. Where should i start?

I'm sorry this is not an issue at all

[vxcall]

Since I've not done this for valorant ever, but generally there're 2 ways.
Either you reverse engineer the valorant client or capture packets using tools like wireshark.
According to this repo's document, the payload is not supposed to be encrypted so I guess either way will work.
but for X-Riot-ClientVersion header and stuff you may need to reverse engineer the client to see where it extracts data from.