In exceptional circumstances an awarding body will produce modified versions of the sets of questions when approached by a centre and following a conversation with the centre.  The complexity of the subject will be another determining factor.

Below is a link to a JCQ document which provides guidance on the assessment arrangements this summer -

https://www.jcq.org.uk/wp-content/uploads/2021/03/JCQ-Guidance-on-the-Determination-of-Grades-for-A-AS-Levels-and-GCSEs-Summer-2021.pdf