Use the standard macOS screenshot option ⇧⌘5. This verision of macOS screenshot includes a menu where you can choose the destination for the screenshot. (Whatever you choose, will be retained for future screenshots until you change the option.) If, doing so, you chose Preview as the destination, the screenshot will open Preview, where you can annotate it, then choose the Share menu in Preview to send the annotated screenshot via Mail or other Share options.
Takes five times longer to describe how this works, above, than it takes to use the feature – built into every Mac.