I typically say “thanks for your message, I’m out until blah date, with periodic access to email” or no access depending. I list contacts who are willing to pitch in if necessary, and list the day AFTER my return that I’ll be able to address messages.
You cannot be sure how quickly your colleagues will respond to messages when you are absent, so avoid promising any instant assistance. Moreover, ensure you take permission from your co-workers before giving their details in the message. They might be too busy to substitute.

Given free rein, I’d absolutely love to tell people that needing me to show them how to do X in Excel is actually not a vacation-interrupting emergency and there are tons of free videos that would explain that, if they did not want to contact the actual departments who handle tech support and training. Or that this project they’ve known about for a month but decided to keep under their hat until it became an emergency is something they’ll need to resolve themselves. But that would not fly at all.
Hello, this is Michael Smith from ABA English. Sorry I missed you. If you have a question about our products, please contact [email protected]. I will follow up once at home. Kind regards.