Yes, you can change the default Purchase Type that displays on 2.0 Shopify themes.
Ongoing defaults to subscriptions, to help you get more subscription sales. To change this, you will need to go into your Shopify theme editor.
On Shopify Admin, under Sales Channel --> Online Store --> Themes
Click on Customize
Once inside your visual theme editor, click on drop down menu at the top that says homepage and click Products.
Now click Default Product.
(If you are not seeing a subscription product appear, click Change in the upper left hand corner to change it to a subscription product.)
On the Product Information section, click on Subscription Plans by Ongoing Subscriptions (this is our "app block")
On right hand side, you can edit the Purchase Type selection.