Hello.
Based on your current config, you can use it at 4k only for office.
When you talk about gaming, there are hundreds of combinations based on current config.
You must understand that you won't play at 4k with this motherboard in this config.
But based on yout current MB, you can upgrade your processor at a max of Core i9 10900k
https://www.gigabyte.com/ro/Motherboard/H410M-S2H-rev-1x/support#support-cpu
Based on your current MB you can add a decent video card that will depends on your taste (AMD or Nvidia) and depending on the budget could vary from an older RX580 8GB to a newer and to date 7900XT - from AMD as for green side it could vary from 2080TI to a newer 4090 RTX.
But ...keep in mind that when you change both processor and video card, your power demand will go very high so the current PSU won't do. You will need at least a 850W gold PSU from a decent producer.
And the last thing you must do is to get at least 16 GB DDR 4 at 3200 or better at 3600 (i recommend 32 gb)