##It is not really possible to use Fey Presence "Out of combat"##

In addition to Dale M's answer, which will often be the simplest method of dealing with the matter, consider the following scenarios:

The Warlock uses Fey Presence on a hostile creature.

This is akin to making an attack. Initiative should be rolled.

The Warlock uses Fey Presence on a non-hostile creature.

There may be other creatures nearby who react to this action. Party members may want to act as well before the ability's effect wears off. Non party members may be see this as a hostile action and decide to attack.

Either way, initiative should be rolled to establish an order for any subsequent activity and to demarcate what can occur before the effect wears off.

In short. you can't use this ability "out of combat" because this is a combat ability and using it would put the character and target (etc) in combat. Again, though, this is the "longhand" form of events. A DM would be wise to identify if anyone else (and any NPCs) would like to act in response and, if not, use the round-equivalent amount of time (six seconds).

It is not really possible to use Fey Presence "Out of combat"

In addition to Dale M's answer, which will often be the simplest method of dealing with the matter, consider the following scenarios:

The Warlock uses Fey Presence on a hostile creature.

This is akin to making an attack. Initiative should be rolled.

The Warlock uses Fey Presence on a non-hostile creature.

There may be other creatures nearby who react to this action. Party members may want to act as well before the ability's effect wears off. Non party members may be see this as a hostile action and decide to attack.

Either way, initiative should be rolled to establish an order for any subsequent activity and to demarcate what can occur before the effect wears off.

In short. you can't use this ability "out of combat" because this is a combat ability and using it would put the character and target (etc) in combat. Again, though, this is the "longhand" form of events. A DM would be wise to identify if anyone else (and any NPCs) would like to act in response and, if not, use the round-equivalent amount of time (six seconds).