Streaming live at 10am (PST) a client to be able to post on her own with photos and so on

I need to help a client and show her how she can be able to post on her own on her website. I need to learn her, to have 2 photos of the same photo, - that is: one preview photo approx. 600x320 pixels, and then a larger photo (if you put your post on Faceook, then the photo has to be 1200x630 pixels) - this larger photo is regarding the whole post. But I have trouble finding an online photo program so that she can cut and reduce the photos she needs. Do you know any online program for this? But it is a little stupid in Webflow, that you have to do this, that you have to customize photos, - One for the preview photo and one for the original photo of the post. If you don’t make your image smaller, then it will weighs too much and the website may run slower in Webflow. But I don’t think that Wordpress has this problem (which I have understood), - they can put just that picture in they want in Wordpress, and they can use it both as a preview and for the actual post in the news … - But what do other Webflow users do? what do your clients do with this problem??
Thanks a lot for helping me :smiling_face_with_three_hearts: :pray:

Can anybody help me??