How to create page with post content in it?

You might get away with shortcodes:

add_shortcode('title', function ($atts, $content = null) {
    $atts = shortcode_atts([
        'id' => null,
    ], $atts);

    $title="";

    if (!empty($atts['id'])) {
        $title = get_the_title($atts['id']);
    }

    return $title;
});

add_shortcode('content', function ($atts, $content = null) {
    $atts = shortcode_atts([
        'id' => null,
    ], $atts);

    $content="";

    if (!empty($atts['id'])) {
        $post = get_post($atts['id']);

        // Full content, disregarding "read more" tags:
        $content = str_replace('<!--more-->', '', $post->post_content);
        $content = apply_filters('the_content', $content);

        // Alternatively, simply use this which respects "read more" tags.
        #$content = apply_filters('the_content', $content);
    }

    return $content;
});

Drop this into functions.php of the theme you are using.

In your page you can then use [title id="42"] and [content id="42"], where 42 is the ID of the post you want to display.