If I end up owing money for the federal income tax, can I pay the full amount off all at once when I submit my efile tax return?

Are there any penalties or taxes on the amount that I owe if I pay immediately on filing my tax return?

Will my return be more susceptible to a tax audit if I owe tax money?

Do I need to change my W4 with my employer so more money from my monthly income gets withheld for federal income tax to avoid a large amount owe for my 2019 tax return next year?

Thanks for any help.