Medievalistic

• Breathing world: vegetation grows and spreads and some materials can decay. (Serene Seasons, Regrowth, Immersive Weathering, Naturalist).
•  Revamped world: the overworld now has multiple new biomes and structures, with the Vanilla ones being totally remade and the new ones adding even more history and mystery to the places you visit, ranging from gigantic temples, to amazing cities, to decaying ruins. Same goes for the Nether. (Terralith, YUNG's mods, ChoiceTheorem's Overhauled Villages, Luki's Grand Capitals, Towns & Towers, Enhanced Dungeons, Castle Dungeons, Awesome Dungeon Ocean Edition, Illager Warship, It Takes a Pillage, Small Horse Stable, The Lost Castle, Valhelsia Structures, Hunter's Return, Incendium).
• Revamped warfare: villagers now have guards and soldiers that you can lead, illagers can attack at night, raids are stronger with new types of illagers and multiple armored foes. Plenty of new fortified locations added for both parties and villages are much bigger. (It Takes a Pillage, Savage & Ravage, Illagers Wear Armor, Villager Recruits, Guard Villagers, Armor of the Ages, aforementioned structure mods).
• Illager activity: ransack villages, pickpocket villagers, can ride ravagers that are domesticated while young, lose reputation in a village if caught stealing. (You Thief!, Steal the Villagers).
• New combat: new animations for combat, better tridents, added lance, revamped horseback combat, shields can parry projectiles and don't have delay, can wear leather, gold, iron and diamond armor over chainmail for better protection. (Better Combat, Better Tridents, Jousting, Horse Combat Controls, Responsive Shields, Shield Parry, Chainmailed).
• Medieval roleplay at its finest: multiple crafting systems were reworked to receive a healhty dose of realism and make them more dynamic and add value to their produce (forging, baking, cooking, farming, butchering, etc), while others are brand new (winemaking, painting, composing music, etc). (No Tree Punching, Salty's Realistic Forging, Bakery, Farmer's Delight, Butcher's Delight, Vinery, Joy of Painting, Music Maker).
• More magic: enchantments have lore behind them and villager and illager magical artifacts can be acquired and used by the player. (Enchantment Lore, Savage & Ravage, Village Artifacts).
• New End experience: the journey to your final destination has been made much longer and harder, with at least 12 different types of eyes being required to open the portal, scattered across the world. (End Remastered, The Lost Castle).
• Quality of life: multiple mods were added to make the experience more convenient and enhance performance. (Too many to list).

It is not recommended to go around picking every single item you see. In fact, do that and you will end up with a full inventory and a very angry golem right off the bat. Instead, respect the property of villagers (or make sure you are not caught stealing) and leave the looting to the abandoned castles and pillager structures, and know when to take something and when to leave it behind. For example, you will come across plenty of pieces of armor, tools and weapons, but if you take all of them, you will have hardly any space for anything else. Same goes for food, materials, blocks, etc. The problem, however, is greatly mitigated by the use of Bags of Holding, Astikor's Carts, and Ender Chested horses, but moderation is still advised.

Speaking of armor and gear, you will notice that making your own is not only much more expensive, but also extremely laborious and time consuming, as it was back in the day (but this time around, it can be quite therapeutic). So give those emeralds the value they deserve, because unless you intend on spending hours in mines, caves and forges, trade will be the best way to acquire gear for you and your soldiers, of which you can have dozens at a time. If you wish to manufacture your own goods, check the small guides added to the tooltips of the items of Salty's Realistic Forging. Also don't try punching trees, as it won't work here. Instead grab yourself some flint and sticks from leaves, and start from there (JEI will help you a ton here).

Moving on to structures, I added so many castles and other structures for a reason: occupy and restore them, to revert their ruinous state and take them back to their glory days, making them livable bases for you and any villagers or other mobs you take with you. Of course, you can still build anything you like, with even some changes to make it a little less difficult, such as World Edit and Forgematica. After all, the villages still need walls to defend against raids, and not all have good buildings already made for you to move and settle in.

With that in mind, you are ready to enjoy the pack to its fullest, playing as whatever you like: you can be a knight errant, travelling the world collecting better gear for you and your steed and delivering villages from pillager oppression, conquering the bastions of undeads and illagers. You can settle in a castle and be the baron of a region, caring for the villagers and doing battle against passing caravans of soldiers. You can become a robber and take for you anything you want without care for good or evil. You can live amongst the pillagers and help them in their raids to win that loot for yourself. You can be an explorer dedicated to finding this world's beauties, or even just be a simple peasant caring for your crops, your animals, or your forge, making the most of the (not always) peaceful life in a village in the countryside.