[Theme Horse Support Team]

hi Antoon

Once go to dashboard-> pages->
there inside blog you are selection the template for full content or blog image medium or blog image large.
Set your template first to full content display.

If still you face the problem then you need custom coding. we recommened you not to change the code but if you want then you can make a child theme and edit the excerpt content and display the full content on the other page.
for more information about child theme

https://codex.wordpress.org/Child_Themes

Regards
Sunil