Just had a pulmonary function test and they said i can inhale normally but i'm not exhaling fully. can anxiety and tight muscles interfere with this?

Maybe: Air-trapping (/"holding") is more common with respiratory diseases (ex: asthma), when it goes in ok, but is delayed exiting. Anxiety/muscle spasm usually plays either both equally (in & out) or more with inspiration. Need to discuss potential causes & treatments w/dr that ordered pfts.

PFT: Yes they can. A pft should be done after you get your tight chest muscles worked on by physical therapy, manipulatio, massage etc and get your nerves worked on by a mental health practitioner. The pft should be done pre and post bronchodilator and then see if you are asthmatic.