sq: 174, car: 36 }

let arr = [{ tp: 12, sq: 174, car: 36 }, { tp: 3, sq: 120, car: 28 }, { tp: 8, sq: 174, car: 36 }];

let res = arr.reduce((accumulator, currentValue) => {
if(!accumulator.tp) accumulator.tp = [];
accumulator.tp.push(currentValue.tp);
return accumulator;
}, {});
console.log(res); //{ tp:[12 , 3 , 8] }