I am playing a Wood Elf Monk. I have a 20 dex, so my initiative is +5. Do wood elves gain any other pluses to initiative?
No, wood elves gain no special bonus to initiative
You don't get additional bonuses to initiative unless you have a feature (racial trait, class feature, feat, spell, magic item, etc.) which says so. Or specifically, gives a bonus to
Initiative rolls (like the Alert feat)
Generic Dexterity ability checks (like the Champions Remarkable athlete feature)
Generic ability checks (like the Bard's Jack of all Traits feature)
For how to boost your initiative into the skies, see: How high can a PC's initiative bonus get?
Wood Elves do not get any special bonuses to initiative
As can be seen under the relevant races section in DnDBeyond, wood elves do not get any bonuses to initiative bar the +2 in their Dexterity scores that all elves get.