It does depend on the purpose of the culturing and to some degree the species. There is unfortunately no "one size fits all" but generally MS media is made at 4.4 grams per L. You can add it to the solution with your agar (check that your pH is correct- usually in the pH7 range but again depends on what you are growing) and autoclave. If you need to supplement with hormones,vitamins, antibiotics, or some carbohydrates you add these after it has been autoclaved using 0.22 uM filters.
Ready to mix MS media available...you should just add it in required volume of water. You can add additives according to your requirement...pH should be in the range of 5-6. For solidifies toon of media, add gelling agent and then autoclave.
Rahul R. Rodge, Anis Mirza, Harjinder Kaur, Lakhesing Girase and Khan Jabroot J. (2023). In vitroRegeneration of Musa Spp. Plantlet CV. Grand Naine by Plant Tissue Culture Technique. Biological Forum – An InternationalJournal, 15(4): 533-538
It depends but normally, for 1 liter of MS medium, mix 1pkt of MS medium in a distilled water (800 ml), add sugar (normally sucrose), vitamins, macro & micro nutrients, amino acids, remaining distilled water & adjust pH 5.7-5.9, add agar (8g)/gelrite(3g), autoclave the medium, after it cools down before solidifying, add filter sterilized aminos, antibiotics, and PGR.