Layman understanding of SHAKE128 XOF
Yes, you can do that as long as you promise to not to use the hash for any other purpose that would be compromised if the shorter hash would leak. However, if you  need fewer than 128 bits then you might as well use SHA-3 and truncate that; it depends on the purpose if SHAKE128 is better than, say, SHA-3-256; they both depend on the same underlying sponge function after all.

Note that neither SHAKE128 or SHA-3-256 output any characters. They generate binary bits or - for most implementations - bytes. The hexadecimal characters that you're showing are just a representation of those bytes.