Hi @Hermoso, Khen Wilson
As far as I know, SharePoint only support for prefix matching. You can specify part of a word, from the beginning of the word, followed by the wildcard operator, in your query, as follows. This query would match results that include terms beginning with "hila", followed by zero or more characters, such as hilarious, hila, hilaa, hilab and so on.
hila*
I have found a similar issue with yours for reference
https://stackoverflow.com/questions/69226066/sharepoint-online-search-file-name-by-middle-characters#:~:text=SharePoint%20does%20not%20support%20suffix%20wildcard%20search%2C%20it,with%20the%20terms%20stored%20in%20the%20full-text%20index.
And here is the document for more details
https://learn.microsoft.com/en-us/sharepoint/dev/general-development/keyword-query-language-kql-syntax-reference
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