Unable to override font-family in lightning-input label using LWC styling hooks

You are trying to override the CSS inside a lightning component. This was easily feasible with aura components, but not with LWC. In order to do that, your best approach would be to load your CSS as an static resource and use the loadStyle method in your rendered callback, instead of using the bundle CSS file.

Bear in mind that THIS is no longer required in LWC CSS files, only for aura.

In your JS:

import myStaticResource from '@salesforce/resourceUrl/myStaticResource';

renderedCallback() {
    loadStyle(this, myStaticResource + '/myStaticResource.css');
}

your CSS file should look something like:

lightning-input-rich-text .slds-has-focus {
  border: none !important;
}

but this part you will need to figure out yourself

You may want to refer to this link: Target inner elements of standard Lightning Web Components with CSS

I would avoid loadStyle "workaround" as it's essentially going around the design of LWC and there's no guarantee that behavior won't change or be blocked in a future update.

Instead, you can create a single css file that leverages these styling hooks and share it across all your LWCs.

Share CSS Style Rules

• cssLibrary
  • cssLibrary.css
  • cssLibrary.js-meta.xml

/* define the styling hooks as you'd like */
:host {
    --slds-c-badge-color-background: #0c9dda;
    --slds-c-badge-text-color: #c21010;
    --slds-c-button-brand-color-background: orange;
    --slds-c-button-brand-color-border: orange;
  }

Then, in your custom LWC - you import the css

@import 'c/cssLibrary';

<template>
    <div class="slds-badge">Traveler</div>
    <div class="slds-badge">Welcoming</div>
    <lightning-button label="click me" variant="brand"></lightning-button>
</template>

You didn't mention community, bu figured I'd point out the --dxp styling hooks for Lightning Web Runtime (LWR) Sites, where you can set a single hook that affects both base & custom Lightning Web Components throughout.

<style>
  /**
   * Scoped to the root of the document and all its descendant elements.
   */
  :root {
    --sds-c-button-color-background: peachpuff;
  }
 
  /**
   * Scoped to any element with the class applied and all its descendant elements
   */
  .container {
    --sds-c-button-color-background: peachpuff;
  }
</style>

Though it does mention

We recommend using --dxp styling hooks to make general changes across the components in you site. But if the --dxp branding defaults don’t provide exactly what you need, you can use --sds styling hooks to fine-tune the appearance of individual components where necessary.