Are there tests available that measure level of antibodies rather than just whether or not you have them? (like for checking after covid vaccination)?

It is not advisable to take an antigen test after covid vaccination to determine if you are immune, because the antibody tests typically measure the antibodies made in an infection with covid 19, not necessarily the one protein made by the vaccine. A low titer of Antibodies will tell you only that you have not previously had the disease, not whether or not the vaccine worked.

There are tests that can measure the level of antibodies to Covid-19. The question is: What will you do with the results? There is no need to take the test. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV and Covid vaccines. Wish you good health!