Juniper provides the option to configure custom ciphers that will be used by the SRX to establish SSL Proxy connections.

You can limit a TLS version by only picking ciphers from that version.

For more information, see:

https://www.juniper.net/documentation/us/en/software/junos/application-identification/topics/topic-map/security-ssl-cipher-suites-for-ssl-proxy.html

https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/custom-ciphers-edit-services-ssl-proxy-profile.html

You will need to add set services ssl proxy profile profile-name preferred-ciphers custom to tell the SRX to use custom ciphers, then specify the ciphers with set services ssl proxy profile profile-name custom-ciphers.

Starting 21.2R1 you can see which version each cipher is from.