Camera send photos from mobile phone?

Hi😌 I transferred all my pictures from my camera (Olympus E-420) to my computer (Lenovo Yoga) and from there to my phone (Huawei p20 Lite). However, although they are like the others in my gallery, I can't send these pictures. Neither via WhatsApp nor Instagram, but via email. If I cut the pictures in my gallery smaller then I can send them, but would rather have the whole picture on it. Why is it that I can't send it? What can I do about it? LG Knutsch28

Decrease the file size.

Goes with photo software. For example, Irfan View.

Menu item "Image", resize, you can choose pixels or cm.

Everything proportional, then nothing distorts.

Probably. Support the mentioned apps and only a certain memory size eg. 2mb?
This is so synonymous by downsizing the pictures synonymous lower

This is a bit strange as the camera only has 10 megapixels. Do the files have a disproportionately large file size over 5 megabytes? Maybe it just helps to save it from a computer program in Jpeg again, with more compression.