add Record "light" effect in post

Go to Adobe Stock and type in : Camera overlay

There are several for free.

Super basic:

1. Create a Graphic with a Text Object that reads "Record" using a sans-sarif font and place that in Video Track 2
2. Create another Graphic with a Text Object that shows a circle and place that in Video Track 3.  The font Webdings with the letter "n" with a red fill at 300 should work.
3. Apply the Strobe Light effect tohe Graphic in Track 3 (the red dot).
4. Place your video in Track 1 and apply a Lumetri preset to your liking.

You really could just make a small red circle in Essential Graphics or with the Ellipse Tool.

These types of things (getting a VHS look, for example) can also be done by adding overlays to your footage. You can find that kind of thing on stock media websites, even YouTube.

If you go the route of using an overlay, or even if you are wanting to make it yourself, you can use blending modes in Effect Controls to make it blend with the footage.