Searches at FamilySearch with the “exact box” unchecked will catch spelling variants.
It is worth noting that the variants they catch may not be the ones you would think that they would. Sometimes the ones they catch are not the obvious ones. Sometimes the ones they miss are ones that are Soundex equivalent to the name being searched for or ones that are really, really close. 
A search for the last name “demarah” and “demarrah” (with the exact box unchecked) did not return the same results in a search of the 1880 census at FamilySearch for individuals living in Clinton County, New York.
It is always worth experimenting with the search options on any site.
We’ve discussed the unexact option on FamilySearch before and the fact that it does not catch all Soundex equivalents of the name being searched.
But all of us, including myself, can occasionally use a reminder.
2 Responses
Does FamilySearch use the typical Boolean characters (*, ?, “”) in their searches? Would using those options improve search outcomes?
Yes they do allow the usual Boolean operators. There are times where those are a more efficient approach–it just depends on the last name and on the spelling.