Depends on the titles in question.
To "play" at 144Hz 4K? No, probably not, most of the time - provided you're prepared to lower in-game settings etc.
To have the best chance of 4K 144Hz High/Max settings on most titles though, SLI 2080TI's is really the only choice these days...... but unless the game supports/scales reasonably well with SLI, it's probably a waste.
Since you have a 2080TI currently, how do framerates look in the games you play?
If you're not coming close to 144Hz, even when lowering settings some..... then a second 2080TI might be worth considering, provided those games support SLI.
Realistically though, SLI is never "worth it" these days... and unless you want to eek out every extra frame, regardless of cost, you're better off saving your cash.