Button on R5 to let go-off canon remote speedlite, as same as with canon 5D Mark IV?

Ronny Wertelaers

Ronny Wertelaers Photography
Apr 21, 2020
With my canon 5D mark IV i could let go off my canon remote speedlites 600EX-rT with strobes of light every time when i hit the depth of field preview button on my body of the canon 5D mark IV. I found this out by accident but this was quite handy as a model light when i put a magmod grid on my flash. To predict where the light will go and set-up my lights. My Mark IV bodies are sold already, so i can't check this anymore.
But i can't figure out to program a button on my Canon R5 now. Is there anybody who knows how to set this up?

Ronny Wertelaers Photography