Should I get the beta 11.3 for my iPhone X??

Read here before doing anything:

Apple Beta Software Program - FAQ

Install the beta software only on non-production devices that are not business critical. We strongly recommend installing on a secondary system or device, or on a secondary partition on your Mac.

Is the public beta software confidential?

Yes, the public beta software is Apple confidential information. Don’t install the public beta software on any systems you don't directly control or that you share with others. Don’t blog, post screen shots, tweet, or publicly post information about the public beta software, and don't discuss the public beta software with or demonstrate it to others who are not in the Apple Beta Software Program. If Apple has publicly disclosed technical information about the public beta software, it is no longer considered confidential.

Read our Terms for full details

No Support and Maintenance; Future Products.
During your participation in the Beta Program or in a particular seed, Apple is not obligated to provide you with any maintenance, technical or other support for the Pre-Release Software.
If, at Apple’s option, such support is provided, it will be provided in addition to your normal warranty coverage for your computer and/or device.
You agree to abide by any support rules and policies that Apple provides to you in order to receive such support.
You acknowledge that Apple has no express or implied obligation to announce or make available a commercial version of the Pre-Release Software to anyone in the future.
Should a commercial version be made available, it may have features or functionality that are different from those found in the Pre-Release Software licensed hereunder.

You will be entirely on your own, if something goes wrong with your device when running the Beta. Unless you are prepared to handle this situations and can stand to be without a functional iPhone for any length of time I would not install the Beta.

About iOS beta software - Apple Support - https://support.apple.com/HT203282

No.

No because we won't listen to you complain about something if you loaded beta software. And it also appears that you aren't an expert and do not have a backup device. So the answer still remains no.