What is the best way to send a lead to a specific landing page based on whether they selected a certain combination of values from a MultiSelect picklist?
Is it just to use the "multiselect field 'contains' X,Y,Z"?
Relatedly, is it wise to do so for each combination? We basically have a set of follow-up questions that we want to ask based on what they select in the multiselect field. For example, if they select Product A and Product B, then we want to ask all the follow-up questions relating to Product A and B. We have 6 different products.
You could use the TY Page Routing choice steps within the Form settings. But I believe this isn't really possible with that functions limits. You need to have it know about a specific field value or CONTAINS at the time of Form Fill and not rely on Smart List like lookups.
You may want to have it do a workflow with a set of Forms and Pages based on the questions. You'll have to manage the branching more carefully or make it simpler.
Don't try to maintain all the permutations -- that's going to be crazy.
Instead, simply forward the value of this field to the follow-up page. You only need one follow-up page and one follow-up form.
Use Visibility Rules on the follow-up form to determine which other questions to ask.