It’s too large by how much? if it’s 10 – 20%, my guess is that you didn’t have the title-safe guides on and/or didn’t compensate for this. If you’re unfamiliar with what “title-safe” and “action-safe” areas are, read this:
https://www2.hawaii.edu/~ghoeffke/video_basics/rules_of_editing1.htm
You can also view the free tutorial at this link (it is the one that says “Safe zones”)
https://www.vtc.com/products/ae65adv.htm
Bottom-line, you’ll usually want the motion that HAS to be viewable to be within these two guides. You can access these guides in After Effects by hitting the apostrophe key on your keyboard.
If it’s a different issue, please advise… maybe someone else has a pointer.
rjf