I would say it's not particularly difficult on it's own, but it has options to make it harder on yourself (that you do need to use if you eventually want to get higher ranks on the levels).

Not so much IMO. FP2 has both several gameplay innovations in terms of difficulty because of Guarding and Revivals mechanics. And quite a lot of variability in terms of "tuning" or "adjusting" the difficulty for player. And I'm not talking about difficulty levels (which are also here, btw).

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For "Guarding" and "Revival" mechanics i'll just paste information from wiki.
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— Guarding[freedomplanet.fandom.com] is a new gameplay mechanic introduced in Freedom Planet 2. By tapping a dedicated button, the player can avoid a certain amount of damage from incoming enemy attacks. The technique will not fully reflect damage from larger or more powerful attacks; however, it will reduce the amount of damage if properly timed. This new mechanic also has a secondary action for each Playable Character:
Lilac: Uses her new Blink Dash Ability
Carol: Summons or stores her Motorcycle after using her new Jump Disc
Milla: Instantly spawns her Phantom Cubes
Neera: Enters her Focus State
In other words - yes, now you can dodge almost any kind of damage for yourself. If you good with timings, of course.

— Revivals constitute another new gameplay mechanic included in Freedom Planet 2. When the character has been defeated, the player is given two options for revival: return to the last checkpoint at full health, or immediately get back up at zero health unless certain health-related items are equipped. This also grants a few seconds of invincibility.
Btw, you can obtain additional revivals by collecting right amount of Crystals (same as you get the Extra lives in FP1).
Ah yes, there's no Game Over in total. So do not be afraid to "lose everything and start game from the scratch".

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And for "tuning" or "adjusting" the difficulty for player I'll explain it myself.
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— One of the main differences with the first game - character "builds". You can equip two special "inventory item's" which give's your character some or other buffs or abilities and make your game easier. The only nuance of this - your level Rank will decreased if you use these items. But if you don't care about Ranks, you won't have any other problems. Besides, any level can be replayed at any time with a different item set (or without them) to get a higher Rank.
— Сonversely, if you even wanted to make your game more difficult and challenger - you can use special "brave stones" for that - they wil make your gameplay more difficult but you will get better Rank at the end of the level; but only if you decide this and choose that "items" so nothing will force you for that.

— Beside of that, you can use special "Potions" to get another kind of buffs for your character: movement speed, jump heigh, attack power, health regeneration for attacking your enemies and other. You can have only 5 of them, but you may mix them in any form: As example, 5 of "attack up" potions increases your physical damage to 20%. Or 5 "Accelerator" potions increases your ground speed to 25%. Sounds pretty cool, isn't it?
And unlike "inventory items", potions do not affect the final level Rank.


P.S.
Yes, this post turned out to be quite long, but it’s better this way than short and not entirely clear information.

not very

Depending on your platforming skills and all, about 25% of FP1's difficulty on Normal mode