Max 401(k) at 61,000

If employee's max 401 (k) deferral (assuming under age 50) is 20,500 and
employer matched 100% for another 20,500, that's 41,000.

If employer matched 6% of employee's salary of 300,000 = 18,000 plus the deferral of 20,500 that's 38,500

How does employee get to the 61,000 maximum contribution limit ?

If employer was just being generous and put in 40,500 (61,000 - 20,500), wouldn't employer have to do the same for all employees?

I'm not a 401 (k) plan expert, obviously ?

The additional to get the max is an employer profit sharing contribution. The employer generally has to do the same for all employees on a percentage of compensation basis. Exceptions apply for age weighted plans and those integrated with social security (if that's still a thing), but all eligible employees will get a contribution.

Thank you