Name of LED text font

There is no such thing as "for Final Cut Pro".

Final Cut Pro will use the fonts that are installed in your mac.

Download the font you like, install it and it will be available.

For example, here there are several fonts you can download.

https://www.1001fonts.com/led-fonts.html

After downloading, double click the ttf files and click Install.

Then start FCP and there you go.

I am not an expert in fonts but that is not much to be going on with... any sort of example where that font, or a similar font was used, may help in figuring out what font you have in mind.

Did you try just googling for "LED font"?

I did and up popped a great number of those...