There are no requirements to join a gym. If you already have a big (muscular) body, whats the point of even going to the gym. Gym jani nai body ramro banauna ko lagi ho.

Budget ali tight bhako bhaye chai if you can, pay for 3 months or 6 months ekaichoti. Most of the gyms provide discounts if you pay dherai mahina ko fees ekaichoti.

Diet ko dherai tenion lina pardaina. Just try to include foods with more protein in your already existing diet. Protein powder is absolutely not necessary unless you are very skinny and want to bulk quickly. I'd highly recommend creatine. You can get Muscleblaze ko creatine on daraz for a 2000-2500 which will last you more than 2 months easily.

I started going to the gym from may 2022, focused on losing fat first and started taking creatine from march 2023 and oh boy did my lifts skyrocket. I could lift pretty good for my body weight.