If you have already filed and have something you need to add or change, then you will need to amend.
Unless you forgot to enter a 1095-A, then you will not amend, you will wait for the letter from the IRS telling you they need form 8965. You can add that now and print it, then when you receive the letter you will have it ready to send.
If you have not yet e-filed or mailed your return and you need to make changes you can simply go back into your return and make the necessary changes.