Will my transplanted beard get thicker? I did my transplantation 7 days ago and they are very thin

You cannot tell how "thick" your beard may be until it grows out in 6 to 12 months.  You also should have been told how many grafts were transplanted so you can have a general idea of what to expect.

Now that you did the beard transplant, you must wait out the results which usually starts growing some 4-6 months before enough hair has grown and then the results will magically appear at 8-10 months from the time you had the beard transplant