How Do I change font-size in vuetify component

To change the font size for a single component, such as a text field, application-wide:

<style>
  .v-text-field input {
    font-size: 1.2em;
  }
</style>

To change the font size within another component, use a scoped style:

<style scoped>
  .v-text-field input {
    font-size: 1.2em;
  }
</style>

For a more generic approach, you can also target multiple component types using .v-input

.v-input {
    font-size: 1.2em;
}

or

.v-input input {
    font-size: 1.2em;
}

Finally, you can also target the labels as well.

.v-input .v-label {
    font-size: 1.2em;
}

You could create a folder called sass, scss or styles in your src directory with a file named variables.scss or variables.sass. And add scss variable $input-font-size: 12px to the variables file. The vuetify-loader will automatically bootstrap your variables into Vue CLI's compilation process, overwriting the framework defaults.

$font-size-root: 14px;
$input-font-size: 14px;

Here you could find details.

Here you could find an example of the variables file.