I have a OnePlus 8 Pro and it works well. Anything after the 8/8 Pro should be fine. Be careful with the OnePlus Nord line as they use Mediatek for some of the models.
On a side note, I wouldn't upgrade to a flagship right now. The last 2 generations haven't been that good because of "bad" processors. On top of that, there's the modem situation.
On one hand we have the affordable and efficient phones with the Snapdragon 865/870 that use the very popular X55 modem. On the other, we have more expensive phones with the hot and power hungry Snapdragon 888 and "Snapdragon 8 Gen 1" (terrible name) with newer and more capable modems.
Now, while the X55 is good, as far as I know it's not capable of aggregating some of the lower bands (it's one of the first 5G modems). This doesn't affect the crazy Three speeds that rely on band 78 alone, but EE for example is already deploying 5G on different bands...
The X65 is better, but then you have to deal with a bad processor because Qualcomm picked Samsung to manufacture the 888/8 Gen1... and Samsung's 5nm node is sh*t when compared to TSMC (they make the 865/870, processors for AMD, Apple, Mediatek, etc). So if you want a better Qualcomm modem right now, you'll need to use a phone with a processor that runs hot and drains your battery.
By the end of the year we should have a few phones available with the "8+ Gen 1" (made by TSMC, not Samsung). Better performance, less heat, better battery life and a modem that should be better at aggregating different bands and provide better speeds.