Trying to check if variable property is in list of values - Mongoengine

I'm trying to query my mongodb db via mongoengine like so

output = Plan.objects(variable_key__in=queryValue, visible_en_backoffice=True).order_by(sortQuery)

The problem is that I'm trying to combine "variable_key" with the "__in" and it doesn't work. Is there any way to do that? I tried making a string like f"{variable_key}__in" and things like that...

Thanks!