:-)

function numbers(str) {
    let numbersArr = str.split(' ');
    let avg = 0;

    for (let i = 0; i <= numbersArr.length - 1; i++) {
        avg += Number(numbersArr[i]);
    }

    avg = avg / numbersArr.length //Avg Number
    let aboveAvg = [];

    for (let i = 0; i <= numbersArr.length - 1; i++) {
        // if (Number(numbersArr[i]) > avg.toFixed(2)) {
        if (Number(numbersArr[i]) > avg) {
            aboveAvg.push(Number(numbersArr[i]));
        }
    }

    aboveAvg.sort((a, b) => b - a); // !!! sort before validations otherwise not correct numbers will be passed on

    if (aboveAvg.length > 5 && aboveAvg.length <= 10000) {
        // let lastFive = aboveAvg.splice(aboveAvg.length - 5, 5); // just splice or slice from 0 to 5
        let lastFive = aboveAvg.splice(0, 5);
        // lastFive.sort((a, b) => b - a);
        console.log(lastFive.join(' '));
    } else if (aboveAvg.length <= 0) {
        console.log('No');
    } else {
        // console.log(aboveAvg.sort((a, b) => b - a).join(' '));
        console.log(aboveAvg.join(' '));
    }
}

Alternative code:

function solve(input) {
    const numberArray = input.split(' ').map(Number);
    const numbersAverage = numberArray.reduce((acc, curr, index) => {
        acc += curr;
        return acc;
    }, 0) / numberArray.length;
    const finalArray = numberArray.filter((num) => num > numbersAverage);

    if (finalArray.length === 0) {
        console.log("No");
    } else if (finalArray.length > 5) {
        const slicedArray = finalArray.slice(0, 5);
        console.log(slicedArray.join(' '));
    } else {
        console.log(finalArray.join(' '));
    }
}