Hello there rust people, i want to edit stack size of specific items in food and tools, i read the plugin details it shows /oxide/data but i cant see any file there which one to edit ? do i have to reinstall plugin to get that file for editing specific ?

To check that the plugin is actually loaded type "plugins" in Rcon and see if it comes up.
It should create a data folder if it loaded correctly, when you edit the data file make sure the plugin is unloaded or it might not save the changes,
To change the stack size(s) in chat use /stack <item name> <amount> and you will get a confirmation in chat that the size has been increased/decreased. the plugin does not have to be unloaded when using chat.
here is a link to items names
https://www.corrosionhour.com/rust-item-list/