fieldgroup > access sub-fields in php?

hi there,

[question]
How can I access the subfields of my fieldgroup in php?
or
Can I use if/then in a field's Viewing > layout > Custom HTML?

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[details]
I have a customfield of type "fieldgroup".
My fieldgroup-field allows multiple values, so each fieldgroup-field-value has - say - a text, a textarea, an image.
So far, I used the field's viewing > layout > Custom HTML to access and render the subfields.

[problem]
Now, one of the subfields (the value-image) became optional. That is a problem, because my Custom HTML then renders empty bootstrap-columns. So I want to make part of the html conditional (meaning not render part of the html when a field is empty).

[alternative solution]
Do I have some kind of "if/then" available in me field's viewing > layout > Custom HTML, maybe like in twig?

hope, above is understandable.
Thanky a lot,
kath

hello we plan to add conditional in html output without tmpl coding but need time