Sirdar santa 4593

For Santa’s beard I have to double strand cast on then just work in knit st. Do I need to knit double stranded the whole way through? X

Long tail cast on is sometimes referred to as a double cast on. There is also a double cast on method for long tail that casts on sts in pairs. Both cast ons continue with a single strand of yarn.
See if the pattern notes at the beginning or at the end of the pattern say anything about the beard cast on. Otherwise, I would tend to cast on with the usual long tail cast on and work single stranded from there on.