Use appropriately sized images so clients can read your proposal comfortably without waiting for oversized files to load.
Steps
Check how the image will appear in your proposal: a wide banner, a package card or another layout.
Export an image close to the pixel dimensions needed for that space. Avoid uploading a full-resolution camera image when it will display much smaller.
Use a compressed image file that still looks clear. Choose a format supported by the image uploader.
Upload it, then preview the proposal at desktop and phone widths.
Check that text is readable, nothing important is cropped and the image loads at an acceptable speed.
Pixels and file size matter more than ppi
Changing an image to 72 ppi does not, by itself, make it smaller on the web. Reduce unnecessary pixel dimensions and file size. Keep the original image separately in case you need another crop later.
Canva, Windows and Mac
Use your design or image application's resize/export controls to reduce dimensions and compression. Menu names change between versions, so use the exported pixel size and file size to check the result.
Keep the proposal usable
Use real text for important prices, terms and actions. A decorative image does not replace selectable packages or add-ons, and tiny text embedded in an image can be difficult to read on a phone.