We actually currently have a Lens Flare Transition in the Adobe Stock tab of the title panel.
To find it:
1. Click/tap the title panel It's a 'T' icon -
- Mobile: on the bottom row
- Desktop: on the right side bar
2. Select Adobe Stock
- Desktop: on the right side of the title panel
- Mobile: click the aarow on the right side of the screen in the title panel, the select Adobe Stock
3. Search for 'lens flare'
4. the "Lens Flare Transition should pop up"
5. Drag it into the timeline above a video clip
Does this satisfy your requests or were you hoping for something else?