On Chrome (my daily driver) I use "Layoutify": https://chrome.google.com/webstore/detail/lay... This will enhance Instagram by a lot and you can simple do a right-click on images (most of the time videos as well, but because IG is constantly changing things so you have to wait for a new update) and then save them.
On Firefox I use this add-on: https://addons.mozilla.org/de/firefox/addon/i... You just have to click on an image and it will open the full-size file in a new tab.
I do not like the normal look of instagram. On instagram also you cannot download. So I use other websites. I used PIKDO but it stopped working. Then I used DESKSTA but it stopped working. Now PIXWOX stopped working. I cannot find a website as convenient as the ones I used before. The others I can find are all worse than normal instagram, or don't work. Do you know an instagram viewer that is similar to the ones I nominated?