Multiclass advice

Hello all I am currently in a campaign at level 9 and am a bit stuck on how to make a new warlock character after my old wizard died(RIP Nigel Fleetfoot). I was considering doing a fighter multiclass because it’s been a while since I played a martial character but was unsure of the split. Any advice on subclass / split would be welcome. My stats are an 8,a 10, a 20, a 18, a 16, and a 14. We have a Druid rogue and a paladin and 2 wizards in the party

what class? this is the warlock section so do you want a warlock?

Standard multiclass with warlock is a 2 level warlock dip to get elditchblas/agonizing blast. If you want to go martial, may i suggest the following

Absolutely max your cha to 17 at level 1. Pointbuy 15, and +2 from background.

2 levels warlock:

Pact of the blade, agonizing blast, pick your favorite for 3rd invocation

6 levels paladin. Use pact of the blade for your weapon attacks, burn your warlock spell slots first when smiting. Get them back on a short rest. At paladin 4, take a half feat that bumps charisma, like fey touched. At paladin 5, extra attack works with pact of blade to make 2 attacks using your charisma. At level 6, your paladin aura turns on, and you have an 18 charisma, giving you and your closest friends +4 to all saves.

You need at least a 13 str for multiclassing, maybe point buy to 15 so you can use plate armor and shield. Con to 14, max cha. Dump int. Dex and wis are like a 10 each so you dont have a penalty on saves and checks.

If you wanna go crazy, play a gnome to get advantage on all mental saves plus your aura.

If you are playing in a campaign with sneaky sneak social stuff, subterfuge and such, put agonizing blast on the Mind Sliver cantrip, and take 3 levels warlock for the Great Old One subclass. You can cast mind sliver without any components, so basically its "subtle", and with agonizing blast, the damage is pretty good.

No components also means you can have a shield and weapon in your hands and still cast it. You dont need warcaster.

If you want to play a martial character, you can do it as a pure warlock with pact of the blade and its dependent invocations. It'll be a very castery martial, but it's doable. (Armor class is your big hurdle. Warlock martials can't take hits like a fighter can.)

Other people are going to suggest various multiclasses, but I'm generally not a fan. (The 1-level fighter dip to get armor proficiencies has some merit, I admit.) But if you're doing things like the above suggested two levels of warlock and six levels of paladin, you're not playing a warlock.

ok, go paladin first. get 1 paladin, 2 warlock, 6 paladin, 2-3 sorcerer (the hightened spell searing smite combos are rediculous) and maybe wild magic, maybe 2 blade singer for the AC buff if you want but I wouldn't advise it. go paladin mostly though. other option is ab lock, that's always nice. but do what you want to do!