Configuring preferences and options in Outlook.com
Exactly the same experience here.
I've got two Galaxy S9s. Both have been crashing with this problem.
I've now got two running with the same version of outlook. One has just one email account attached - as MS exchange one - and the other has that account and a SMTP account attached too. The second one has just crashed again after two days - storage had grown to abut 8Gb - which seems to be the limit for the phone/OS combination before it stops working. Now reinstalled it with just the one exchange account connected to see how it goes.
I've tried to raise this with M$ through the help feature in outlook on the phone - but apart from the acknowledgement, I've had no follow up from them.
I hope somebody can find a fix for this.
I have a Pixel 3 XL with 64GB. For the last 10 days I have a slightly new effect. After I have to reset "Clear Outlook storage, Power On/Off, Reinstall account" the User Data stays at about 300-400 MB for a couple of days then shoots up all of a sudden to 9-10 Gigabytes, near the boundary of crashing the system by using up all 64GB (100%). Then suddenly, shoots down again to 300-400 Megabytes for two days. The cycle then repeats 2 days very low, 2 days very high. I am waiting for the next high to cause a necessary account reset. I guess this must be a Microsoft problem, not Android. I wonder what Outlook is up to. Maybe downloading all Archives for some unknown reason???