Without knowing the model it's hard to say for sure, but I'm going to assume you live in the U.S.
The bad news: consumer CRT's (TV's) in the U.S. are doable but challenging if you want to get a good picture. As you noted without component the only way to get a really great picture is to hack the TV. You can use the S-Video to some success, although I would have to lean on someone else's experience converting an RGB signal with minimal loss to an S-Video.
The good news: You can hack the TV's OSD (on screen display chip) to inject an RGB signal. It requires getting comfortable with knowing the components of a CRT (especially the dangerous ones), and requires comfort in looking at schematics and soldering. There is a dedicated subforum to the topic here:
https://shmups.system11.org/viewtopic.php?f=6&t=56155. There are also numerous Youtube videos showing people doing it as well if you search for TV RGB mod. I haven't performed one myself yet, but plan to do so in the future. There are folks here that have done it as well.
Arcade monitors, Sony PVM's, and Consumer TV's with component make it easier (although with component you will have to buy a Transcoder).
There is also the additional option of doing a tube swap (I haven't done this either yet). Which means you buy an arcade chassis (Printed Circuit Board typically underneath the glass tube, which will also have a neckboard and other components), and take the tube from the consumer TV and fit it to the arcade chassis. Again this involves a more firm understanding of CRT components and understanding taking the proper safety measures, and measurements on the tube to match it to a chassis.
This may all be a bit much if you are starting out. It depends on how far you want to go to get an accurate Arcade picture/experience.