There are 2 good ways to get shiny Pokemon in scarlet and violet. Both ways require the shiny charm for best odds.
1. The wild method
First you identify an outbreak of the Pokemon you want. Then you make a Sparkling Power sandwich. You can go here for recipes
https://www.dexerto.com/pokemon/best-shiny-sandwich-recipes-in-pokemon-scarlet-violet-easy-recipes-for-sparkling-power-3-2007534/ . Then you go to the same outbreak you identified and destroy 60 Pokemon in the outbreak. Then despawn and respawn the Pokemon until you find a shiny. Save before catching it then catch it. with a shiny charm your odds are 1/512. Without it your odds are 1/1365.
2. The Mesuda method
To get a shiny with this method, you need other than a shiny charm but you also need to breed your Pokemon and one of the Pokemon needs to be from a different country. Then you breed the two and have a 1/512 with the shiny charm and without is 1/2048.