Well, some games will likely be CPU limited in some places. However, a GTX 1650 would still be a significant upgrade and let you play at higher graphics settings / framerates in a lot of games a lot of the time.
Warzone isn't particularly demanding on the CPU - it's no Assassin's Creed Origins/Odyssey - so you would be fine.
The 1650 is easily twice as powerful as something like the R7 370, and while the old FX series CPU would sometimes limit your performance, you're still going to get a lot out of a 1650 overall.
I'd go with the upgrade.
Make sure to run
DDU before swapping your GPU as AMD and Nvidia's drivers are different and you don't want your old GPU's drivers to interfere with the smooth running of your new GPU.
