I’m looking for a way to have a text box appear based on the previously selected answer.

[Trevan Householder_Isos-Tech-Consulting_]

For example, if on a select list they choose “Other”, they should have a way to fill in a field to give that information.

[Deleted user]

No Custom Field like that, the closest you can get is the Cascading Select (2 list boxes), but it's not a text box.