Use the following dateFns functions to get the components, then concatenate them together with the strings.
let x be the smaller year, y be the larger
save differenceInYears called on x and y which gives the whole number of years in a variable
pass x and that as a parameter to addYears, assign to x
call differenceInMonths on x and y, save
call addMonths on x and that saved number of months
do the same with differenceInDays and addDays, differenceInHours and addHours
Now x is less than 60 minutes away from y, so call differenceInMinutes and you're done (assuming your countDown is down to the minute).
Here is your example as run on runkit.com to illustrate the method.
var dateFns = require("date-fns");
var x = new Date();
var y = new Date(2022, 2, 6, 0, 0, 15);
var temp;
temp = dateFns.differenceInYears(y, x);
var result = temp + " years ";
x = dateFns.addYears(x, temp);
temp = dateFns.differenceInMonths(y, x);
result = result + temp + " months ";
x = dateFns.addMonths(x, temp);
temp = dateFns.differenceInDays(y, x);
result = result + temp + " days ";
x = dateFns.addDays(x, temp);
temp = dateFns.differenceInHours(y, x);
result = result + temp + " hours ";
x = dateFns.addHours(x, temp);
temp = dateFns.differenceInMinutes(y, x);
result = result + temp + " minutes ";
x = dateFns.addMinutes(x, temp);
temp = dateFns.differenceInSeconds(y, x);
result = result + temp + " seconds";
console.log(result);