英文信下款

Your Sincerely - very polite , writing to a person very important like your boss
Yours faithfully - you are writing to a person more closer like maybe you friend.......
You could also use " Your friend" , Your Daughter" , Your Son" ........
Also when you are writing to a person very close to you , you could use " hugs and kisses", "love"...........
Also when you are writing a letter to a person to wish them luck you could write " Best wishes" or 'All wishes" .

if you use dear manager, i think u still use " yours sincerely"

Dear Sir/ Madam - Yours faithfully (Formal)
Dear Ms./ Mr. XXX - Yours Sincerely (Formal)
Regards/ Best Regards - (Informal)