I have 3DS (including a set of twins). 3yo and 1yo so there were 3 under 3 for 6 months.
DH and I both work full time, he is on site and I am hybrid. 3yo at preschool full time. Twins at childminders 3days a week and home with me 2days during my Wfh days.
I don't find life too hectic. so I want to try and help here as much as I can.
Our house is a divide and conquer approach.
I'm in charge of all cooking. DH is in charge of all cleaning. I usually focus on the twins, DH focuses on the toddler. So we have our (very loosely) allocated children for putting down for naps, food, clothes, getting out of the house, wakings etc.
Strict nap routines mean all DCs are in their own beds by 7pm latest every night. So DH and I spend 3 hours a night doing our own thing - TV, video games, scrolling etc. 7.30am wake up usually. Twins still wake up a couple of times at night for bottles /changing.
Food is delivered. All batch cooked. Buy food which is pre-cut saves a lot of time. We also have a chest freezer in the garage with pre made meals ready to go for any busier days.
DH does quick mini cleans throughout the day eg cleans the sink whilst brushing his teeth in the mornings. Admittedly there isn't much of a deep clean that happens at all, but the house generally is of a decent standard.
3yo is in charge of tidying up toys before bed, so we are never left with a bombsite at the end of the day.
What in particular are you finding difficult OP? I'd love to give some suggestions for how we do it.