How to become a world chess champion?


learn it all...
Improving Your Chess - Resources for Beginners and Beyond
https://www.chess.com/blog/RussBell/improving-your-chess-resources-for-beginners-and-beyond
seriously.....never stop striving to learn what you don't know.....at least, insofar as it is applicable to your goal...

If you are serious, find a chess club in your city (or in the nearest city), and start playing real games.

No you can't. The truth hurts.
12 and 1000 rapid. EVERY modern world champion was a Chess prodigy. Gukesh was GM by 12. Ding was a GM by 17. Carlsen was a GM by 13. Anand at 18. You shouldn't give up, but I wouldn't recommend getting your hopes up.

12 and 1000 rapid. EVERY modern world champion was a Chess prodigy. Gukesh was GM by 12. Ding was a GM by 17. Carlsen was a GM by 13. Anand at 18. You shouldn't give up, but I wouldn't recommend getting your hopes up.
Botvinnik learned the game at age 12.

12 and 1000 rapid. EVERY modern world champion was a Chess prodigy. Gukesh was GM by 12. Ding was a GM by 17. Carlsen was a GM by 13. Anand at 18. You shouldn't give up, but I wouldn't recommend getting your hopes up.
Botvinnik learned the game at age 12.
Mikhail Botvinnik was a prodigy.

Plus, OP only plays Blitz and bullet. They are stable at 900. Along with that, they can’t break 1100 on rapid.

12 and 1000 rapid. EVERY modern world champion was a Chess prodigy. Gukesh was GM by 12. Ding was a GM by 17. Carlsen was a GM by 13. Anand at 18. You shouldn't give up, but I wouldn't recommend getting your hopes up.
Botvinnik learned the game at age 12.
Mikhail Botvinnik was a prodigy.
As I said, he didn't even know the rules of chess when he was 12 years old. He learned the game a few months later.

No you can't. The truth hurts.
12 and 1000 rapid. EVERY modern world champion was a Chess prodigy. Gukesh was GM by 12. Ding was a GM by 17. Carlsen was a GM by 13. Anand at 18. You shouldn't give up, but I wouldn't recommend getting your hopes up.
Shutup. Don't tell woman what to do

Well, 12 is very late. Most world champions started at a single digit age.
Bobby Fischer started at age 6, Garry Kasparov at the latest at age 7 when he got into Botvinniks chess school, Magnus Carlsen at age 5. Those are AFAICS the three greatest chessplayers of all time.
So - best of luck. Maybe you have the necessary talent, and the insane amount of will and endurance necessary.

Guys it's never too late to learn even you are old. That 12 year old kid wants to learn and he have a dream of becoming a GM. It is not impossible to get a title of GM if he focus on improving his skills. So don't belittle a 12 year old kid and he still learning.

My suggestion is you focus on 20/40/40 rule. 20% for opening, 40% for the middle game, and 40% for the endame totalling to 100%.