Hi,
1. I want to create a landing page. This should be the default home page – just when I type the url it should display this home page or landing page.
After creating a landing page, you can refer to WordPress’ very own documentation on how to set it as your home page.
https://wordpress.com/support/pages/front-page/
2. I want to display primary navigation menu only on the home page.
You can do a Layout Element that disables the Primary Navigation Menu.
Read more about Layout Element here: https://docs.generatepress.com/article/layout-element-overview/
First, make sure the Elements module is enabled on Appearance > GeneratePress.
After successfully enabling it, you can create Layout Elements through Appearance > Elements.
On your Layout element’s “Disable Elements” tab, check “Primary Navigation”.
On your Display Rules tab, set Location to “Entire site” and set Exclude to “Front Page”. Make sure to save it.
This disables the primary navigation on the entire site except your front page/home page.
3. Also are there any resources to create a landing page.
Technically, landing pages are basically the same as any page you create on WordPress. The main difference between any basic page and a landing page is mainly on its purpose.
As for designing & aesthetics, this is pretty subjective. Googling keywords like “WordPress landing pages” will most likely give you the things you need.
As for technical stuff, feel free to ask us.
A wise man once said:
"Have you cleared your cache?"