@Zhuo Chen , As TP (thank you) highlighted, currently, you need to use CLI/PowerShell method to set TLS version to 1.3. The portal drop-down option to set 1.3 version will be enabled in a few months*, we do not have an exact ETA to share.
Note: the timeline is just an estimate, it may change depending on the myriad factors.
If the answer helped (pointed you in the right direction) > please click Accept Answer - it will benefit the community to find the answers quickly.