Build an obstacle course in the living room
Second the den building
Teddy bears picnic for lunch, or just pretend play with a tea set
Crafts - salt dough, which can then be painted the next day. Play doh. Get some stuff like threading beads/peg boards etc.
Musical instruments out of pots/pans.
Do you have baking beads or similar? Fill them in a pot then give dc a spoon and another pot and ask them to transfer.
On rainy days get your wellies on and go puddle splashing. If big puddles get some glitter in them.
Get a tray and put shaving foam on it - drive cars through it. Then get a bucket and wash the cars.
If she's into dolls, give them a bath.
Sensory tray with things like spaghetti, Cheerios, rice on it. Let her play with fingers, spoons etc.
Is there a park near you? Do that a couple of times a week if so.
I was at home for 5 years and now work in a pre-school so I've picked up some tips over the years 😂. I totally agree though that giving it some structure is the key. Do something outside on a morn or afternoon, then something crafty/pretend play on the opposite side of the day.
I also don't think a couple of chunks of TV a day is a bad thing at all.