aufrecht
upright
In a straight, vertical posture; not bent over or lying down.
Er saß aufrecht auf seinem Stuhl und hörte aufmerksam zu.
He sat upright on his chair and listened attentively.

upright
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upright
In a straight, vertical posture; not bent over or lying down.
Er saß aufrecht auf seinem Stuhl und hörte aufmerksam zu.
He sat upright on his chair and listened attentively.

The word is composed of 'auf' (up) and 'recht' (in the sense of straight). So it literally describes a straight, upward-facing position or posture.
Bitte halten Sie den Rücken beim Heben aufrecht.
Please keep your back upright when lifting.
'Aufrecht' (upright) is very often used as an adverb to describe how an action is carried out. It then appears unchanged after the verb.
Trotz des starken Windes ging er aufrecht weiter.
Despite the strong wind, he kept walking upright.
The meaning 'bestehen lassen' (to keep in force/maintain) exists only in the fixed expression 'etwas aufrecht erhalten' (to maintain something). The object stands between the two parts of the expression.
Die Firma erhält ihr Kaufangebot trotz der neuen Informationen aufrecht.
The company is maintaining its purchase offer despite the new information.
The meaning 'ehrlich' (honest) or 'charakterfest' (of strong character) is a transfer from physical posture. A person with a 'straight' posture is considered honest and principled in the figurative sense.
Er ist ein aufrechter Mensch, der immer zu seiner Meinung steht.
He is an upright person who always stands by his opinion.
right now / straight
'gerade' and 'aufrecht' can both describe something that is not crooked or bent over. 'gerade' is more general and fits lines, paths, edges, or objects that are not curved. 'aufrecht' usually describes a vertical posture: a person is sitting or standing without being bent over, or an object is standing upright. Learners may confuse the words because both have to do with a straight form. When it is about the shape of a line or object, 'gerade' often fits. When it is about an upward posture, 'aufrecht' is more precise.

Im Wartezimmer sitzt sie aufrecht auf dem Stuhl.
In the waiting room, she sits upright on the chair.
Beim Einkaufen sucht er morgen ein gerades Brett für das Regal.
When he goes shopping tomorrow, he is looking for a straight board for the shelf.