Using page templates
Page templates can be applied to your store's pages to style the content created in Shopify's rich text editor. Templates can change the layout of pages, such as the position or width of the elements and can also append things like contact forms.
To change a page's template, go to store admin Online store > Pages and select a page that you would like edit. Scroll to the Template field and select an option from the drop-down menu and click Save.
You can create a contact page using the page.contact template. This will add a contact form to that particular page.