Like if most days as a hobbyist, using under 30V, and I only really care about mV or 100's of nV accuracy when they are 1st turned on......they can all do that cold, right ?
But I see tho, I have DMMs that can do 4-5d pretty good, but none are a modern bench DMM. IDK, maybe I really should just get an older 6.5d meter, and get a new 5.5d meter.
Browse this thread and you'll see that high-res DMMs aren't generally a daily driver. However, regarding the requirement for warm up, it really depends on your needs and your definition of "good enough." For example, if absolute accuracy isn't critical (which it usually isn't for hobby use), then a cold DMM will give you a reasonable result to 3 or 4 digits. You don't even need to switch it into a lower-resolution mode. That way, you can see the rate at which the value changes as the meter warms up and to what resolution you feel comfortable with the measurement. Using a higher NPLC setting can also be helpful, if the additional sampling time isn't a hindrance to your tasks.
If the absolute value is important to you, then I'd recommend running some tests at different warmup times from cold compared to when the meter is fully warmed up to determine how long you need to wait for your particular device to achieve your desired accuracy.
Note that even handheld DMMs, which are generally used right away from turn on, have a warmup time for full accuracy and when calibrating/adjusting.