How to add multiple plugin in tinymce?

You only need to separate the plugins with a space. in your case, it would be:

<script>
    tinymce.init({selector:'textarea',
    plugins: "code image",
    });

You are specifying the plugins property twice. It should only be there once and then multiple plugins should be specified in that property. According to the documentation you need to be using a comma or space separated string, or an array of strings. Try this below:

<script>
        tinymce.init({selector:'textarea',
        plugins: "code image"
        });
</script>

https://www.tinymce.com/docs/configure/integration-and-setup/#plugins