Here are some resources for free motion graphics, transitions, titles and lower thirds.
Lots of free options, included with Creative Cloud subscription. Great place to start looking for titles and graphics for your projects.
Mostly pay-to-download, but a good number of free graphics, transitions and templates as well.
Like Motion Array, primarily a pay-to-download platform but they offer a starter pack with five free graphics files.
Some templates are available as Premiere project files that you can open on their own. Most will be .mogrt files that you’ll need to add to your essential graphics panel. Many of them will require you add a new font to your computer for the graphic to display correctly—here’s how to do that on a Mac and on Windows.