Wow WordPress is so complicated, there are a zillion different ways to change the maximum image upload size.
With WordPress 5.x single site, while you can edit the maximum file size in wp-config.php, the easier way is to use a plugin that sets it called brilliantly, upload-max-file-size
With Multisite WordPress 5.x, this again moved, but it is way down in the Network Admin/Settings/Network Setup/Maximum Image Size entry. The default is 1MB which is a little small. 4MB works pretty well with today’s high speed broadband.
This guide is written to provide all possible solutions for increasing the maximum upload size of media files in WordPress.
— Read on www.cloudways.com/blog/increase-media-file-maximum-upload-size-in-wordpress/
There are a few ways to handle images that you upload (all of my recommended WordPress Plugins are in WordPress.org account (https://profiles.wordpress.org/richtong/#content-favorites):