Is there a way to lock text glyphs to preserve size in an order with variable strings?

What you're attempting to do, I have not done. For my project, I left each portion of the text under control of its own Sequence Text, but you should find it possible to link one scale setting to the other under a single control. [The behaviors you're showing me are not set up as I would recommend, so I'm not sure what you have will work as you might expect...]

The big *hint* here is that you need to separate the Sequence Texts from each other, and *one* way to do that is to set them up is to set up the Animate parameter for Word or Line, which means that when you create the text, if you only ever use one word, you can use the Word animation and type the text as t<space>ypograh<space>y, use the Custom Speed control to select the first word for the "T" and apply the behavior and set the Custom Speed on the second STBehavior to select the last word for the "Y".

There is a bug in Custom Speed. Motion will always try to reset it to a default pre-keyframed animation from 0 to 100(%). You have to manually defeat that by setting it to a value *without keyframes* and save it (at which point, Motion will reset it to animated... it's quite aggravating, but the saved version will be saved without the keyframes). [I think you can just right click the downward caret at the right edge of the parameter and *Reset Parameter*, even after rigging to clear it.) Another way to defeat this insanity is to RIG the Custom Speed with a widget Slider, and the best way is a combination of both! So only expect to use this in FCPX or expect to have to undo the auto-keyframing Motion does each time you use it in Motion.

In order to use Custom Speed for a "set value", you will also need to set the Start Offset to the last frame of your project (in other words, the animation can *never* start.

You can also do this by "Line" (using a return character in place of the space), but you will have to readjust the first and last "words" by Sequence Text > Format > Position > Y and the Sequence Text > Format > Position > X parameters (and these should probably be rigged as well with the Maximum values available that you are likely to need.)

(See what I mean about just using Transform Glyph?)

BTW - I'm not exactly sure the information above is 100% accurate. — YMMV (but only slightly). I was working on this several months ago after creating the original attempt some months before that. I have not released the effect because of some of these problems I kept running into, even though I could do all those different variations with the single same Title template. Even if Apple fixes Custom Speed "behavior", I currently cannot upgrade past Mojave, so it wouldn't make any difference. And, if you experience that bug, by all means, send them Feedback and let them know that it's just wrong!!

Very good — you're well on your way to getting to here:

These are all generated from *one* Title in FCPX (not a different title for every variation!) All from the same Sequence Text setup.

Stranger Things was set up to be used "by" Lines and the starting string was

S R

trange

things

the rest were set up "by" Words, so "hide" was "h i de" and galileo was "gali l eo", etc. and individual characters were set up as complete words to be selectable by Sequence Text.

I found that separating out sections by "words" (using spaces [and other diacriticals]) is **much easier** to select segments. You will have to publish controls to readjust the horizontal spacings, though, but it's nearly impossible to select two or more characters in a word or a sentence with reliability, but separating out a group of characters by making a "word" makes selections a snap.

This version of Stranger Things uses two Title instances, one for Stranger Things and the other for the overline and underlines:

the over/underlines were created with the vertical bar character '|' (but I don't remember if by words or by lines — I crashed the library and had to "retire" it.)

Believe it or not, you are not that far away from building a title like this one. You've already got the core of it in place! Going forward, go piece by piece. Study what you've got, then add the next steps. Don't try to throw everything together at once. The original version I built was not capable of animation, I added all that last. Do a search on "word play examples" (images) and find some examples to try to accomplish, like:

(ELE V V ATOR)

and one of my favorites:

I've found I can accomplish almost everything with **three** Sequence Text behaviors on the title text and that's about all you'll have room for when you finally publish that many parameters! However, it is really cool to pull off these kinds of text effects without piling on several layers of titles (or generators) in the storyline.

Have fun! This particular project is an education in itself!

The short answer is yes...

The long answer begins with: It's probably not worth the effort. It is far easier just to format the text by using the Transform Glyph tool and selecting the beginning and ending character separately and using the onscreen controls to size and position the end characters. Type in all lowercase and when you use Transform Glyph, set the All Caps option. Make a note of your scalings (you can watch parameters in real time).

The longer answer is you can actually use more than one Sequence Text on a text object, use each sequence text to select portions of the text for transforms, but this is exceptionally complicated to set up.

https://twitter.com/sightcreations/status/1384059019636088838?s=20

and a second demo:

https://twitter.com/i/status/1390582403870208001

All of these examples are single text objects (formatted/created in FCPX, but the title project also works in Motion).