Hello FirstTimeSwiss
This depends on the museum or activity. Please see the respective websites.
For some, you get free admission, for others you must present your Swiss Travel Pass to the cashier in exchange for a ticket.
What concerns Lindt & Sprüngli, I have no information. I asked them via e-mail as there is zero information on that on their website. What concerns Lindt & Sprüngli: book in advance, they are often sold out for days. I will be back with news as soon as available.
Kind regards;
Roland