This normally should work, although it will get all other memory to lower speed matching your outdated RAM sticks specification (but most likely with a bit better latency / CL than "higher" speed module).
I've mixed RAM brands in my 7060 SFF with i7, two of SK Hynix 8GB (with total=16GB) 1Rx8 (single rank) 3200 and two of Crucial 2666 16GB (32GB total) 2Rx8 (double rank)
both pairs are JEDEC standard Non-ECC, non-XMP, Unbuffered sticks.
Two different sets are running in sync successfully at 2666 speed in Dual mode.

2133 is Mostly not working depending on the ram and CPU.

Core I5 will want 2666 ram 1.2v

Core I7 will want 2933 ram 1.2v

XMP and 1.35 to 1.7v is never happening on optiplex or xps or precision models.

If you use 100 percent 1.2v JEDEC 2933 ram it will work on the old and the new without error. Otherwise its low and slow beep beep beep beep and flashing amber power button.

Crucial RAM 16GB DDR4 1.2v CL22  2933MHz or 2666MHz CT16G4DFD832A

https://www.amazon.com/dp/B07Q4FX2D5/

@speedstep - TS is talking about 7060 model, those use 8th gen CPUs (doesn't support 9th gen), therefore stock speed is 2666 for i7, not 2933, none of i7/i9 with or w/o "K" document RAM speeds above 2666 as per intel specs.