I'm gonna roll up a wizard, and give him a fighter's name. Something like "Huxley the Brave," or somesuch. And right out of the gate, I'm going to give him proficiency in heavy armor and/or martial weapons (using the "Custom Lineage" rules in Tasha's). I'm also going to give him the Soldier background. None of this Arcana and History stuff, I'm going with Animal Handling and Athletics.
Remember, this is going to be a wizard with a spell book, familiar, all that...except Huxley will look and act like everyone's stereotypical "fighter." That spellbook? It's a leather-bound tome of battle maneuvers, enemy tactics, and field position diagrams. His familiar? A falcon, because that's what certain highly-trained military units carry in this kingdom. His arcane focus: an ale mug, a medal of valor, a ceremonial longbow, whatever, I'd just pick something that any fighter would have.
Whenever someone refers to my character as a "wizard" I will firmly (and loudly) correct them. This is a fighter thank you very much, please get it right next time. No I do not need to prepare my spells, I don't even know what that means. Now if you'll excuse me, I need to go study my book of military strategy for an hour or two.
And when it comes to magic, I will rename and reskin all of his spells to match. It's not Magic Missile, it's "Arrow Volley." Its not "arcane recovery," it's "military insight." He didn't just cast "Fog Cloud," he cast "Fog of War." That wasn't Longstrider, that was--actually, 'longstrider' works just fine. (Same for Shield, Snare, Catapult, Jump...heck, this is going to be easier than I thought.) The vital part is to make sure I describe them as not looking magical at all. When he casts Magic Missile, I will describe him literally shooting arrows from an actual bow, and those arrows cannot miss and deal 1d4+1 force damage each...not because they're magical, no sir, it's because I know Special Combat Techniques or whatever. When Huxley casts Cause Fear, he literally scares his enemies with his hulking muscles and booming voice, not some weird arcane force. When he scries through his falcon, he's actually just concentrating really hard on, um, geography and...enemy tactics and...stuff so that he can...you know what it's not important the point is he knows what's over the next hill sheesh.
The important thing is--and I cannot stress this enough--it's vital that Huxley does not look, act, or present himself as 'magical' in any noticeable way, ever. He doesn't 'cast spells,' he uses special training and techniques. He doesn't 'add spells' to his 'spellbook,' he transcribes the military secrets of like, ancient dwarven kingdoms or whatever. 'Counterspell' didn't 'negate' his magic missile Arrow Volley; he just happened to see someone staring at him and babbling some kind of nonsense, and it gave him performance anxiety and he lost his mojo for a sec, it happens to everyone at least once, give the guy a break.
I'm confident that this character would be balanced (if not slightly overpowered), and completely playable. After all, Huxley would be a wizard in every mechanical way! The only changes I have made are flavor, description, vocabulary, and so forth; everything else is RAW.
So: why would I do such a thing? Why would I go through all of these mental gymnastics and extra effort just to make a "wizard" that plays like a "fighter"?
I honestly have no idea. But apparently it's the hottest topic of 2023.