My 2 year old is coming to her first game next month, really because I’ve run out of babysitters and my wife had to work.
My 9, 7 and 5 year old all have season tickets with me so reckon she’ll be fine as they’ll help if needed. I think for a while you have to accept that smaller kids won’t be enthralled for a couple of hours but will enjoy bits of the experience. For the rest of the time I’ve taken sticker books and they’re happy enough.
The three older ones now watch the whole thing and count down the days to home games. I think that’s really helped too with them getting out to other things, I’ve had my 7 year old for a full day at the cricket and he loved it, I think a lot of that was because he knows how sports events work - that if he watches he gets a lot out of it and he’s not going to get an ice cream or hot dog every 20 minutes.