apex code to fetch the state based country picklist using cutsom object

I was able to achieve this with LWC, I am not sure if this is any relevant. Adding the comment for future references. Most of the code are already available in the internet.

<template>
    <template lwc:if={picklistValues.data}>
        <lightning-combobox name="country" label="Country" value={selectedCountry} placeholder="Select Country" options={picklistValues.data.values} onchange={handleCountry}> </lightning-combobox>
        <lightning-combobox name="state" label="State" value={selectedState} placeholder="Select State" options={states} onchange={handleState}> </lightning-combobox>
    </template>    
</template>

import { LightningElement, wire, track } from 'lwc';
import { getPicklistValues,getObjectInfo  } from 'lightning/uiObjectInfoApi';
import COUNTRY_CODE from '@salesforce/schema/User.CountryCode';
import STATE_CODE from '@salesforce/schema/User.StateCode';
import USER_OBJECT from '@salesforce/schema/User';
export default class CountryStateTest extends LightningElement {
    selectedCountry;
    selectedState;
    countryToStates;
    states;
    @wire(getObjectInfo, { objectApiName: USER_OBJECT })
    objectInfo;
    @wire(getPicklistValues, {
        recordTypeId: '012000000000000AAA',//This is the sfddc default recordtype for this function as per documentation
        fieldApiName: COUNTRY_CODE
    })
    picklistValues;
    @wire(getPicklistValues, { recordTypeId: '012000000000000AAA', fieldApiName: STATE_CODE })
    wiredStates({ data }) {
        if (!data) {
            return;
        }
        const validForNumberToCountry = Object.fromEntries(Object.entries(data.controllerValues).map(([key, value]) => [value, key]));
        this.countryToStates = data.values.reduce((accumulatedStates, state) => {
            const countryIsoCode = validForNumberToCountry[state.validFor[0]];
            return { ...accumulatedStates, [countryIsoCode]: [...(accumulatedStates?.[countryIsoCode] || []), state] };
        }, {});
    }
    handleCountry(e) {
        this.selectedCountry = e.detail.value;
        console.log(`Country ${this.selectedCountry} event ${JSON.stringify(e)}`);
        this.states = this.countryToStates[this.selectedCountry] || [];
    }
    handleState(e) {
        this.selectedState = e.detail.value;
        console.log(`State ${this.selectedState}`);
    }
}