Was in a similar position just over a year back (one kid, 2yo) and got a 2019 5F ST Lux. Great car and the size is bang on for a small family. The little one needs an epic amount of stuff, so have filled it to capacity more than a few times. The large flat boot floor is great for nappy changes/roadside emergency potty breaks - not sure if you get the level loading with a hatch?
Continuing with the grim but inevitable side of parenting, the kid loves the car which rides better than most SUVs which she'd throw up in more often than not. But with the rare occasion when she has thrown up in the Leon, the leather seats are handy at the clean up stage (though we put down a towel under the car seat to make everything easier).
As estates go, Leon ST is a bit smaller/narrower, but that’s actually pretty handy getting the kid out in car park spaces and the interior is plenty big for one. Not sure I am brave enough to see how it works with two