It sounds like you are talking about D&D 5e 2024 rules. Under those rules, chains are described as follows:
As a Utilize action, you can wrap a Chain around an unwilling creature within 5 feet of yourself that has the Grappled, Incapacitated, or Restrained condition if you succeed on a DC 13 Strength (Athletics) check. If the creature’s legs are bound, the creature has the Restrained condition until it escapes. Escaping the Chain requires the creature to make a successful DC 18 Dexterity (Acrobatics) check as an action. Bursting the Chain requires a successful DC 20 Strength (Athletics) check as an action.
You'll want to manage a few separate things:
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A free hand. If you are grappling with one hand, you need another hand free to apply chains. That means you cannot be weilding a shield or a weapon, unless you happen to have some extra appendages (though I think those only exist for legacy 2014 species right now). So if you're Dwarf, no shield.
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Action economy. A Utilize action and an Attack action (the latter of which allows you to make an unarmed strike to perform a Grapple) both cost your one Action for the round. You'd need access to some sort of ability that lets you Utilize as a Bonus Action instead. Thief Rogue 3 providea Fast Hands, which does exactly that.
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DM fiat for easy access to multiple chains. If it is free, or at most only costs an object interaction to get a new chain from your bag, you're golden. If it costs more action economy to get a chain from your bag, your DM might effectively limit how many chains you can "wear" for easy access. In a home game, this might be a no brainer, but in a westmarch it would likely require a server ruling.
Your best bet to make this work would be a multiclass of Thief Rogue 3, and the rest in Battle Master. The way you could make your action economy work, once you got to Rogue 3 Fighter 5, would be to:
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hold a Chain in one hand, and have the other free.
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Take your Action to Attack.
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Use the first attack of your Extra Attack to Grapple.
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Assuming you succeed on the grapple, use your Bonus Action to Utilize the chain and Restrain your opponent.
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Release your grapple, and use your one Object Interaction for the turn to draw a Finesse weapon elegible for Sneak Attack,
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Use the second attack of your Extra Attack to attack with that weapon with advantage (adding Sneak Attack and optionally a Maneuver).
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Edit: Optionally, sheathe the weapon for free after this attack, to get both hands free again. You can do the full combo on round 1 and 2, but then have to attack first, sheathe, and then grapple on round 3 (assuming you wanted to do the combo again). Chances are you'll still be working normal attacks on the first target tho, so its unlikely that the economy of drawing, sheathing, and getting chains every round will truly be necessary.
I think that if you are playing this character from early levels, I would take Battlemaster to 5, and focus on just attacking and using maneuvers to topple or some such, and then at 5 attack and topple, then maybe grapple to keep them prone. Work on the Rogue levels after you have Extra Attack, to be "feature complete".
You might be able to make some version of this tactic work across two rounds earlier than level 8, but I think it would be more complex and prone to getting disrupted. You can do it once using Action Surge onxe you reach level 5 tho, which is nice.
If your DM is really kind, they might let you Utilize Chains as a BA even without Thief 3. Or maybe as a homebrew Maneuver. That'd probably be the best way to play that fantasy!
It's cool that Vestige warlock can get Spirit Guardians via War domain spells, and the Vestige itself seems pretty big on HP. Can take pact of the blade to be a melee bruiser, with the vestige backing you up from range. I haven't checked to see if there is any other way to get both SG and Extra Attack by level 5 using only 2024 core-and-expanded rules yet, but this is an exciting development!