Big dog sized. Can be docile enough to be a pet. Wouldn't recommend it though.
According to Wikipedia:
Adult males are around 2.4 m (7 ft 10 in) long from nose to tail tip, and females average 2.05 m (6 ft 9 in), with overall ranges between 1.50 to 2.75 m (4 ft 11 in to 9 ft 0 in) nose to tail suggested for the species in general.
[30][31] Of this length, the tail typically accounts for 63 to 95 cm (25 to 37 in).
[32] Males generally weigh 53 to 72 kg (117 to 159 lb). Females typically weigh between 34 and 48 kg (75 and 106 lb).
[32][33] Cougar size is smallest close to the
equator and larger towards the
poles.
[34] The largest recorded cougar, shot in 1901, weighed 105.2 kg (232 lb);
I have pet one before in captivity. Even coming close enough to do so in the wild would be suicide. I was somewhat young at the time, like middle school, but it seemed massive to me then. They are larger than their weight would suggest, because of how lanky they are. And they are all over North America. From Florida all the way to the opposite corner. I don’t doubt it was one, and am not surprised police and drones could not find it. They are near impossible to find if they don’t want to be found. I’ve heard crazy statistics about how frequently hikers out west are stalked, and I’m sure they are exaggerated, but what I’m sure is not exaggerated is the fact that it does happen and that those it happens to nearly never know.