Here is a help center article on names that begin with Mac, Mc, El, Van, and so on:
How do I index a surname with a prefix, like El or Mac?
Published November 23, 2020
It can be difficult to tell whether a space exists between a prefix and the last name. Record it either way. The system overlooks spaces, so type what you see.
I'm going to tag your good question for @Indexing Chat
When I index names, I only put a space between different parts of the name if it looks like it was originally written (or typed) as separate words. Different individuals with the same last name often differ as to whether or not elements of that last name should be spaced out. For example, one person might spell their last name "Van Deventer" while another spells it "Vandeventer".
Oh, I didn't know the system overlooked spaces! Thanks, Melissa!