Render an image that is located inside a Paragraph that is inside an Entity Reference
Assumming a firm content type has field_paragraph which holds field_image of 1 image

for comparison to get firm name in twig file you will use

{{node.field_firm.entity.title.value}}


for firm paragraph image field value 

{{node.field_firm.entity.field_paragraph.entity.field_image.entity.uri.value}}


To get the rendered image 

{% 
  set firm_image = {
    '#theme':      'image_style',
    '#style_name': 'thumbnail',
    '#uri':        node.field_firm.entity.field_paragraph.entity.field_image.entity.uri.value,
    '#attributes': { class: 'yourclass' },
  } 
%}
{{firm_image}}


Alternative way to get referenced entity fields