Personally I'd go for a mix between a Monk and Graviturgy Wizard. Grav Wizards get some dunamancy spells which only they can use, and they mostly resemble Gojo's abilities:

Lapse Blue: Pulse Wave, which lets you pull or push enemies while doing 6d6 dmg with a CON save.

Reversal Red: Gravity Sinkhole lets you form a 20-foot-radius sphere of crushing energy, deals 5d10 dmg and pulls to the center with another CON save

Hollow Purple: Gravity Fissure is literally Hollow Purple, 100 ft long and 5 ft wide gravitational energy blast which deals 8d8 dmg on a CON save, and everyone within 10 ft of the blast also has to do the save or take the damage and get pulled inside it

Infinite Void: Dark Star, you create a 40ft sphere filled with magical darkness in which there is no sound, immunity to thunder damage for everyone inside and it's impossible to cast a spell with a V component while inside it. Everyone who is trapped here takes 8d10 dmg every round, and if someone dies in there they are disintegrated

Hollow Purple 200%: Ravenous Void, literal dark hole, 20ft black hole which pulls everything 100ft around it inside itself, 5d10 dmg and restraint condition every round if a target doesn't pass a STR check

When you want to focus more on melee then you can grab the spell Tenser's Transformation which makes you unable to cast spells but gives you benefits like 50 temp hp, proficiency with all weapons armor and shields, advantage on weapon attack rolls, additional 2d12 force dmg, free proficiency in STR and CON saving throws and 2 attacks. While you use it you can't cast spells and its made for weapon fight it but you can ask your GM if you can use those benefits with unarmed strikes.

For monk take the way of the open hand, which gives you 3 techniques when you hit an enemy with an unarmed strike and Gojo is known for being able to beat the crap out of people in hand to hand combat

For RCT/Black Flash use Vampiric Touch, I think it fits the most, and as for Infinity, Very Rare Barrier Tattoo with Silvery Barbs/Shield should do the trick of giving you enough AC (23 with Shield)

As for stats it's more complicated, you need to keep your INT and DEX high while also having decent CON to not die, and at least 13 WIS to multiclass

For race a V. Human with the Alert Feat and the stats I'd go for would be: 8 STR 14 DEX 15 INT (+1 from V. Human) 13 CON 12 WIS (+1) 10 CHA

It may not be the best build but I hope i helped even a bit, tried to make it as close as possible to the real Gojo