When I had my son, I thought I was going to go full on with santa, snowy footprints, have a family member dress up so he gets a glimpse, etc. really make it real.
But then I quickly felt uncomfortable about that. It doesn't feel right to really make children 100% believe in it, especially pushing that belief when they were older.
Looking back at my own Childhood - there was never a moment of "Oh, he isn't real, I've been lied to" instead, there was just a gradual realization over time that comes with age. No heartbreak, no tears, etc.
I think this was because my parents always did santa with a "wink" - They never said he wasn't real, and I probably did believe it for a while, but it was always presented with a bit of a air of humour/story-telling etc. around it. Not as absolute fact.
E.g. if my son asked me is santa real, I'm not going to look him dead in the eye and say "Yes! Santa is absolutely real!" Instead I say things like "Well, do you believe he is real?" or "Well, I don't know, but I wouldn't want to take a risk!", or "Well he better be, because otherwise I'll have to buy the presents!" etc.
That combined with the slip ups.. the times when you say "Oh, I got you that for Christmas" and the child says "didn't santa get me that?" - oh yes, sorry.. and the dodgy mall santas, and the movies, and the older children etc.
All of that combined, should not create the situation of absolute 100% belief, that then leads to heartbreak. But instead creates a not-so-believable story that children naturally grow to understand can't be real as they get older.