We had a massive lifestyle change/ shift 18 months ago, I won't go into reasons but EVERYTHING changed, jobs, house, climate, lifestyle, but not country etc etc.
Lots of active and decided upon change, including clutter/ belongings overhaul. We're a family of 4, so things can overrun.
Some things that have helped:
TV cabinet with 6 shelves, 3 shelves each have a box with a lid, 1 for cables/ chargers, 1 light bulbs, 1 batteries. None of these things go anywhere else. Not DS rooms, not upstairs.
Hallway, 4 sets of hooks on wall, 1 set low enough for DD. Each person has their own set, max 2 coats and 2 outdoor pants each, 1 pair trainers, 1 pair snowboots. All out of season clothes, shoes or outdoor gear is washed and packed away, 1 box per person in the store cupboard upstairs, box is labelled.
All of clothes are seasonal, so shorts shirts etc are packed away until summer and same happens in winter.
We do lots of things like this, especially organising seasonally, so bikes, helmets outdoor furniture is cleaned and packed away before winter and winter gear, sledges, skis, ice skates, snowboards are all ready and available.
Anything too small, not used or unwanted is either sold on second hand site or donated.
But to be honest, the absolute biggest change to reduce "stuff" after the clear out, was to stop buying. Honestly, you don't need it. All 4 of us used to love going shopping, those pokemon cards or football cards have to go somewhere when you open them, that extra t-shirt or jumper, the new shoes or whatever. It all needs to take up space in your home.
We moved somewhere where there is no shopping unless you want a 3 hour each way journey. Once we stopped buying stuff, there was less stuff in the house.
It's saved us money and stress from having crap all over the place. But now when I do buy something, it's absolutely something I need and have space for.