If I do a border run after my 60-day visa, will I get another 30 days in Thailand?

If you need an extra 30 days get a 30 day extension for 1900bht

You only get another visa if you apply for one. Do you mean visa or exempt entry?

you don't get a visa, you get a visa waiver.

How long have you spent inside Thailand in the past 12-18 months? That's more relevant than I've only done one border run. But one border run implies that you entered Thailand, received a 60 day visa exempt stamp and did a 30 day extension, then flew to Myanmar for another 60 day visa exempt stamp and have possibly had a 30 day extension on that as well. If you were to leave and return now you would possibly get another 60 day stamp (it's not yet dropped to 30) but if you did it under your own steam it's highly unlikely. If you use a border bounce company or a safe entry service they will get you in (or not assist you) but the price will depend on your history.

"I have a 60 day visa after flying in from Myanmar" . . did you enter on a visa, or did you enter visa-exempt ? When you enter visa-exempt, you do NOT receive any visa. You just receive a stamp that says "admitted until" - this is a stay permit, not a visa

"I have a 60 day visa after flying in from Myanmar " . . . . . so you entered Thailand on a single entry 60-days Tourist Visa ? Why don't you apply for the 30-days touristic extension first, before you do a border run? You could do the border run SAFELY with an agent (with a "Visarun Company") and get 30 more days when entering visa-exempt. This would be a 120 days holiday (60+30+30) but don't expect to be issued another 30 days extension - this will be upon the sole discretion of the Immigration officer and it also depends on your previous one-year period touristic stamp history

You'll only get a visa if you apply for one. But if it changes you can enter visa exempt for 30 days and extend that for extra 30 days at the local immigration.

Today & at the moment

You will still get 60 day Visa exempt Stamp