As I understand, in 1x mode, the safe voltage is 5 volts and it can be used up to 35 volts.
The usable input voltage range is -5V ... 5V. Voltages below -5V are limited to -5V and voltages above 5V are limited to 5V, so it makes no sense of applying higher voltages, this is just a safety margin.
Voltages outside the safe range of +-35V (can) destroy your device.
With a 1:10 probe the limits are 10 fold, i.e. measure between -50V..+50V, the safe range is
theoretically -350V..350V. However, I would suggest keeping the limit of +-50V as values outside this range will not give useful results. Also check the safe operating voltage of the probes. Please be very careful with high voltages.
You can check the principle schematics of the oscilloscope in the user manual on page 20:
https://github.com/OpenHantek/OpenHantek6022/raw/main/docs/OpenHantek6022_User_Manual.pdf