I really struggle with our house (narrow/Edwardian, very little purpose built storage) and I have 3 young children so my time and energy is limited. I'm very much still learning, but I do know that it helps not to drop the ball too much if I/we can help it. The moment I "allow"/put up with mess, it seems to breed...
Key things that I find help:
"A place for everything and everything in its place".
Having decent storage is useful and with children that also means storage that is (at least mostly) easily accessible for them to use and tidy up by themselves/as directed. I currently feel overrun by toys/"stuff" after having my third child last year, so I'm now in the process of sourcing some more storage units (probably more of the cube variety) that better make use of empty space we have, to keep toys sorted properly and all in the right/same general place. I also plan on decluttering (some toys to go to a charity shop) and rotating items (some toys will go in the attic for a while, properly labelled and with a note made about what's up there!).
Acknowledge that if certain things constantly end up in the same old pile, you might as well address the fact that human nature means we take the path of least resistance. For e.g. we have an under stair cupboard where shoes should be kept, but reaching the rack in there is slightly tricky due to the way other things are stored out of necessity and it's not a convenient place... so "every day" shoes just end up chucked in a pile in an alcove. I've just ordered a shoe storage cabinet to sit in the alcove which should resolve the issue. I also hate that the children's first instinct is to throw their coat on the back of a chair when they get in, but I can't reasonably expect much different because they don't have their own hooks at an easy to reach height. I'm addressing this, too.
My children can be quite destructive/make a game out of pulling every single toy out once my back is turned (e.g. gone to the loo, busy making dinner, etc.), despite my efforts to remind them that the consequences will be having to tidy up for a long time with a grumpy mummy... The thing that helps with this one is a) making sure I do actually make them do the tidying if this happens, even if it's laborious and annoying for me to direct (otherwise the lesson just doesn't sink in) and b) anticipating moments where this is likely to happen (e.g. the witching hour) and trying to redirect focus.
I try to ensure we have at least a few minutes every day when the children tidy and/or do something to help with the house (e.g. empty the bottom drawer of the dishwasher, lay the table, wipe something clean). This has massively helped and they mostly enjoy it (we play the "tidy up song" on Alexa, give lots of praise, give stickers for especially good jobs or unsolicited tidying, etc). At the moment my children are at the ages where "doing a job for Mummy" can seem quite exciting, so I'm trying to take advantage of it and make it normal in advance of the years where they may not be so keen (especially if it doesn't become a habit)... during the day I'll routinely ask them to use the dust pan and brush, take something to the bin, take something upstairs, help me put away the laundry, etc...
A friend has a rule of only getting a toy/set out once something else has been put away. I'm working towards this myself (currently tricky as things are mixed up chaotically due to lack of decent storage and me letting things get out of hand/bad habits form... but the children are getting much better now that they play a regular part in tidying up properly themselves).
In terms of having a pristine house that looks like a show home... the only people I know who have homes like this hire in help. All of them have cleaners and one has both a cleaner and a nanny. I am trying to make my peace with aiming for "tidy enough" and "clean enough" because I'd rather spend my time with my children vs. spending lots of time cleaning so things are spotless because I can't afford a cleaner (choosing my priorities)! Additionally, many of the people I know with very tidy houses have a lot more space which a) allows for more/much better storage and b) dilutes the amount of perceived clutter (e.g. if we spread out our "standard" clutter in their space, it would seem minimalist, if that makes sense). They often have playrooms, too.
The other thing I'd say is that appearances are deceiving... we always have to tidy and clean before people come over. I know (because they've told me) that friends (particularly the ones without cleaners) are in the same boat. Our houses certainly don't always look as lovely as they do when we have guests! Similarly, my friend who had the most spotless house during maternity leave only had a spotless house because she struggled with PND and becoming obsessive about cleaning was how she tried to cope.
Having said the above... I do always feel better when the house is tidy (and it always used to be tidy pre-children), so I am trying not to accept default untidyness and am actively battling it.