<?php
namespace Bwip\ApiEndpoints\Model\Api;
use Magento\Framework\Exception\InputException;
use Magento\Framework\Exception\NoSuchEntityException;
use Magento\Framework\App\RequestInterface;
use Bwip\ApiEndpoints\Api\CustomInterface;
 
class Custom implements CustomInterface
{
    /**
     * Returns greeting message to user
     *
     * @api
     * @param string $name User name.
     * @return string Greeting message with users name.
     */
    protected $request;

    public function __construct( 
        RequestInterface $request,
        array $data = []
    ){
        $this->request = $request;
    
    } 
    public function info(){
        $post= $this->request->getPost();
        
        $info[] = array('message' => 'GET Working.', 'status'=> 0);
        return $info;

    }
    public function data(){
        $post= $this->request->getPost();
        
        $info[] = array('message' => 'POST Working.', 'status'=> 0);
        return $info;

    }

}

<?php
namespace Bwip\ApiEndpoints\Model\Api;
use Magento\Framework\Exception\InputException;
use Magento\Framework\Exception\NoSuchEntityException;
use Magento\Framework\App\RequestInterface;
use Bwip\ApiEndpoints\Api\CustomInterface;
 
class Custom implements CustomInterface
{
    /**
     * Returns greeting message to user
     *
     * @api
     * @param string $name User name.
     * @return string Greeting message with users name.
     */
    protected $request;

    public function __construct( 
        RequestInterface $request,
        array $data = []
    ){
        $this->request = $request;
    
    } 
    public function info(){
        $post= $this->request->getPost();
        
        $info[] = array('message' => 'POST Working.', 'status'=> 0);
        return $info;

    }
    public function data(){
        $post= $this->request->getPost();
        
        $info[] = array('message' => 'GET Working.', 'status'=> 0);
        return $info;

    }

}

Interface file

interface CustomInterface{

    /**
     * GET for Post api
     * @param string $value
     * @return string
     */

    public function info();
    /**
     * GET for Post api
     * @param string $value
     * @return string
     */

    public function data();
}

My di.xml file

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <preference for="Bwip\ApiEndpoints\Api\CustomInterface" type="Bwip\ApiEndpoints\Model\Api\Custom"/>
</config>

Interface file

interface CustomInterface{

    /**
     * GET for Post api
     * @param string $value
     * @return string
     */

    public function info();
    /**
     * GET for Post api
     * @param string $value
     * @return string
     */

    public function data();
}

My Model

<?php
namespace Bwip\ApiEndpoints\Model\Api;
use Magento\Framework\Exception\InputException;
use Magento\Framework\Exception\NoSuchEntityException;
use Magento\Framework\App\RequestInterface;
use Bwip\ApiEndpoints\Api\CustomInterface;
 
class Custom implements CustomInterface
{
    /**
     * Returns greeting message to user
     *
     * @api
     * @param string $name User name.
     * @return string Greeting message with users name.
     */
    protected $request;

    public function __construct( 
        RequestInterface $request,
        array $data = []
    ){
        $this->request = $request;
    
    } 
    public function info(){
        $post= $this->request->getPost();
        
        $info[] = array('message' => 'GET Working.', 'status'=> 0);
        return $info;

    }
    public function data(){
        $post= $this->request->getPost();
        
        $info[] = array('message' => 'POST Working.', 'status'=> 0);
        return $info;

    }

}