Are some acts, such as going to congregational prayers with the intention of showing consistency to friends, or raising the volume of the Qur’an in the car to inform people of its virtue and manifest Islam, considered showing off (riya’)?

A Muslim's actions should be solely for the sake of Allah, without any ostentation. Displaying good deeds is not considered ostentation if the intention behind it is solely to draw closer to Allah, without seeking praise or commendation. It is even commendable to display good deeds if it encourages others to emulate them and follow suit, as the Prophet, peace and blessings be upon him, said: "Whoever introduces a good practice will have its reward and the reward of those who act upon it until the Day of Resurrection." As for competing in acts of obedience, Allah has urged us to do so, saying: "So compete in good deeds" and "Hasten to forgiveness from your Lord." Listening to the Quran aloud for others to hear is praiseworthy as long as it does not cause annoyance or harm to others, based on the Prophet's saying, peace and blessings be upon him: "There should be no harm nor reciprocating harm."