Custom Permission:

HTML:

<template>
    <lightning-card>
        <lightning-input
            type="toggle"
            label="Test Permission"
            checked={isTestPermEnabled}
            disabled>
        </lightning-input>
        <lightning-input
            type="toggle"
            label="View All Data Permission"
            checked={isViewAllDataEnabled}
            disabled>
        </lightning-input>
    </lightning-card>
</template>

JavaScript:

import { LightningElement } from 'lwc';
import hasTestPermission from '@salesforce/customPermission/Test';
import hasViewAllDataPermission from '@salesforce/userPermission/ViewAllData';

export default class PermissionCheck extends LightningElement {

    get isTestPermEnabled() {

        console.log( 'hasTestPermission is ' + hasTestPermission );
        return hasTestPermission;

    }

    get isViewAllDataEnabled() {

        console.log( 'hasViewAllDataPermission is ' + hasViewAllDataPermission );
        return hasViewAllDataPermission;

    }

}

Output: