To be brindle he needed to have at least one brindle parent. Brindle is known in Mastiff and Bullmastiff but not too common.
I would say Bull Arab pigging x. Or Brindle bull breed x. .
He looks too small to have much pure mastiff in there and I would think it may be a few gens back. And if he does, the width of his jaw would suggest Bullmastiff rather than Mastiff (English). Possibly Dogue but honestly he looks more likely to have Boxer than Dogue in the mix.
The other possible input is American Bulldog type, as his head looks very bulldog to me.
There's no clear sighthound in there. Whoever said Wolfhound or "Staghound" needs a breed identification refresher. His structure doesn't lend to sighthound type at all. The Bull Arab has sighthound blood way back, with a bunch of other input - but is selected to a bull breed type with longish legs. This boy has shorter legs as well which makes sighthound even less likely (or more far-distant!!)