Fidelity first, then size
PDF is a container. If you start from a crushed social-media download, no setting invents pixels. Shoot or export a larger master, convert once, then compress only if Gmail still rejects the attachment.
Sample before the archive
Run one page. Zoom to 100%. If faces look plastic, the source was already small — Image Enlarger will not rescue a 640-pixel crop. Folders of 40-megapixel files belong on merge, not in one Edge tab.