I have three modes with keys and phone in common.
1 Dogwalking cross-body bag with poop bags, treats, grooming equipment, Labello, pen and notebook. Bank card in phone case.
2 Ryanair size backpack with padded compartment for tablet (not often used) inside are: foldable shopping bags, sunglasses, reading glasses, tissues, notebook, mega-purse with ID, CC, licence, loyalty cards, donor card etc. Double sided pencil case with perfume, makeup, tissues, aspirin on one side, tri point pen, mini screwdriver (!), pencil with rubber, USB charger and earphones on the other. Water bottle if I remember.
3 “Good” handbag with nicer versions of the above.
I think the idea of the mega-purse is dying out but I’ve used the rectangular style for decades and it acts as a catch-all for receipts etc. It also holds my phone if necessary.
When the kids were small I had a Mary Poppins bag: wet wipes, hairbrush, snacks, school letters, emergency sewing kit, change for swimming pool hairdryer etc etc etc.