adding an extension to my main url

Site URL: https://www.lofftwen.co.uk

Hi there

My current domain is www.lofftwen.co.uk which is focused on holiday lets. I want to have a second website without losing the lofftwen.co.uk suffix that is focused on ecology. This would be www.ecology.lofftwen.co.uk. 

Is this possible through squarespace? I've tried looking on their help guides but can't find what I need.

Thanks in advance.

Will 

Yes. You can build a second website and give it a ‘subdomain’ like ecology instead of the www subdomain.