How to change textbox into dropdown in PHP

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PHP

I'm totally new in PHP and I need to change following code which is textbox (input box) into a dropdown box, but I have no idea how to achieve this. someone help me, please. thanks

global $post;
$location = isset( $_REQUEST['location'] ) ? sanitize_text_field( $_REQUEST['location'] ) : '';
$current_page_id = isset( $_REQUEST['current_page_id'] ) ? absint( $_REQUEST['current_page_id'] ) : ( ( $post && $post->ID ) ? $post->ID : 0 );
?>




<!-- Search Text Field -->
                <div class="opalhotel-form-field">
                    <label class="opalhotel-form-lable"><?php esc_html_e( 'Location', 'opal-hotel-room-booking' ); ?></label>
                    <div class="opalhotel-form-field-group">
                        <input name="location" placeholder="<?php esc_attr_e( 'Enter your keyword', 'opal-hotel-room-booking' ); ?>" value="<?php echo esc_attr( $location ) ?>"/>
                        <?php if ( isset( $_REQUEST['hotel_id'] ) && $_REQUEST['hotel_id'] ) : ?>
                            <input type="hidden" name="hotel_id" value="<?php echo esc_attr( $_REQUEST['hotel_id'] ) ?>" />
                        <?php elseif( isset( $_REQUEST['room_id'] ) && $_REQUEST['room_id'] ) : ?>
                            <input type="hidden" name="room_id" value="<?php echo esc_attr( $_REQUEST['room_id'] ) ?>" />
                        <?php endif; ?>
                    </div>
                </div>
                <!-- end Search Text Field -->

What I have tried:

i tried few things but i cant figure it out