One D&D is introducing a number of optional changes to Dungeons & Dragons, one of which involves making musical instruments a lot more useful than they currently are in D&D 5e. There are some magical musical instruments that can be useful to a D&D party, such as Pipes of Haunting, but these are the exception, rather than the rule. D&D 5e hasn't done much with regular musical instruments, but that's going to change in the upcoming D&D 5th edition revision for its 50th anniversary in 2024.
In the current version of the D&D 5e Player's Handbook, the equipment section has a selection of musical instruments on offer for the player to buy, including bagpipes, flute, lute, and pan flute. They are classed as Tools, which means players can have proficiency in a type of musical instrument, allowing them to add their proficiency bonus when using them as part of a skill check. There are some classes that offer instrument proficiencies, such as the bard, while some Backgrounds also offer them, like the Outlander.
In the current D&D 5e rules regarding regular items, weapons, and tools, instruments don't actually do much. A bard can use an instrument as their spellcasting focus, but it's not required for them to cast spells. An instrument will commonly be used as part of a Performance (Charisma) check, but chances are, if someone is making such a check (like a bard), then they're already going to have a huge bonus to the roll. The use of musical instruments is hyper-focused in D&D 5e, but that will soon change, as the first Unearthed Arcana update for One D&D on the official D&D Beyond website has a great option for making them useful.
One D&D's Musician Feat Makes Instruments Incredibly Useful To Parties
One D&D has introduced new Feats to D&D, as well as changed how they work. Feats are no longer optional and every character gets to choose a Feat at level one, from a select number that is designated as 1st-Level Feats. One of these new low-level Feats is called Musician and it provides proficiency with three instruments. If the party takes a short rest or a long rest, they can use the Musician Feat to play soothing music during the rest, granting Inspiration Points to a number of party members equal to proficiency bonus. The DM might decide that playing bagpipes in the dungeon or in the wilderness is likely to draw attention, so players might be careful about when they want to use this Feat.
One D&D made Inspiration Points a main rule as well, and players can spend them on gaining advantage on d20 roll. This means the warriors and rogues of the group can be given some free uses of advantage for attack rolls, skill checks, or saving throws, and it's now an easily replenishable resource. This means musical instruments are now incredibly useful to a D&D party and any player who is making a character who focuses on buffing their allies should make the Musician Feat a must-have choice for their next Dungeons & Dragons character.
Source: D&D Beyond