The suffix field should only be used for a suffix that the person actually used when writing his or her name.
Here's the link to the help page: Help:Name Fields (wikitree.com)
Which says:
Suffix appears in every name display on WikiTree, even when a Prefix, Middle Name, or Current Last Name do not appear. Therefore, it is generally reserved for suffixes that are an essential part of the person's name. It is usually a Suffix at Birth, e.g. Jr. It may be a suffix or post-nominal acquired during a person's lifetime if the person themselves would have included it when writing their full name, e.g. Bt for Baronet. It should never be a suffix acquired after death or a suffix the person themselves would not have used.
If the person had multiple suffixes, it should generally only be the most important one for identification purposes. Others should be described in the biography. If a Prefix could substitute for a Suffix, that is recommended.
Suffix is limited to 10 characters.