Hi there and welcome to the community!
A quick search tells me that dash charge was developed by OnePlus itself for the OnePlus 3 and 3T up to the 6 and 6T, and it’s all.
Qualcomm devices like the FP3 use Quick charge, which is a different method than dash charge.
I wouldn’t be sure at 100%, but I think I can say at 99% that your charger won’t work for dash charge, though I think it will work for normal charge.Edit: not even, intensity output too high.
I would like to add that I have kept charging an FP3 for months with an old iPod (2005) charger that is definitely not QuickCharge compatible (first I used a no-name USB-C cable, now Fairphone’s own USB-C cable). It just takes this charger a bit longer to give the FP3 a full charge.
If I am not mistaken, this should not matter because the electronic device to be supplied with power takes as much as it gets, but not more than it needs.